117 Most Frequently Asked RDBMS Interview Questions And Answers

Introduction

It's no secret that the present job market is extremely cutthroat, and overcoming the first obstacle of job application could be a challenge in itself. Once you cross this first hurdle, the hard way towards finding a new job career has now barely begun. The RDBMS field is among the highly competitive fields, specifically because so many job hunters are vying for such limited job openings. You’re required to be at your best so as to emerge from the crest of the competitors. The easiest way to achieve this is to be well-versed using RDBMS interview questions. 

In this blog post, we’ll go over the 117 RDBMS important questions you will likely be asked during an interview and how to answer them. Also, consider joining a credible data management courses to sharpen your skill sets.

Let’s get started with the RDBMS questions and answers. This series of RDBMS basic interview questions and RDBMS technical interview questions both of them will cover in-depth information about relational DBMS.

RDBMS Basic Interview Questions and Answers

RDBMS stands for relational database management system that stores the data in tables, and you can easily access it even through another database. It is the basis for sql, oracle, Microsoft Access, and IBM DB2. excellent RDBMS knowledge is required for RDBMS-related job roles. 

Below is a quick list of RDBMS interview questions and answers:

Q1). Give a quick idea of the term RDBMS.

RDBMS refers to storing or managing data across numerous database tables. The most advantageous part of relational database management is that you can state relationships between various data entries with the help of tables. These relationships can usually be expressed using values and not pointers.

Q2). How will you define a relational database model?

It defines the relationship among different databases and how they are connected. When multiple databases are connected, it creates flexibility and can be used within a software app as needed.

Q3). Tell me about RDBMS components. 

Each relation in an RDBMS is given a “Name” that will be unique. In each relation, rows and columns represent attributes, and rows as Tuples. Other RDBMS components include RDBMS table, touple, column, domain, schema and RDBMS constraints.

Name => Attriutes => Tuples

Q4). Give a quick idea of the term Normalization.

It is a data organisation process where data is organized in such a way that it can minimize redundancy. It divides the database into multiple tables and defines logical relationships among them.

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Q5). Name different Normalization types that can be used with RDBMS.

Each has its objectives and purpose. So, you must understand them one by one before implementing it with the database. The following are the different normalization types:

• 1NF (First Normal Form) 
• 2NF (Second Normal Form)
• 3NF (Third Normal Form)
• BCNF (Boyce-Codd Normal Form)
• 4NF (Fourth Normal Form)

1NF , 2NF, 3NF, 4NF, 5NF, BCNF, ONF, DKNF

Q6). Have you ever used a Stored procedure (SP) in RDBMS?

Yes, I know about the SPs and worked on them during my training. An SP is a group of SQL statements that can be used together to act. It accepts input parameters to be used with different scenarios. SPs are considered an added advantage to ensure a database's integrity.

Q7). Give me a quick idea of the E-R Model.

E-R model stands for entity-relationship model which explains closely related things in a particular domain of knowledge. A fundamental ER model comprises of different entity types and mentions the relationships which could exist among the entities. 

It consists of entities and relational objects. Entities can be understood by the collection of attributes in the database.

Q8). Tell me something about various data abstraction levels.

In RDBMS, data can be abstracted at three different levels. They are given below -.

Physical Level -> Logical Level -> View 1, View 2 & View 3

The physical level is available at the bottom, giving you a detailed idea of the data storage. The Logical level at the next stage finds the logic among data tables and how to group similar data for easy access. At the top, there is a view level that gives information about the complete database and various views of a database.

Q9). Define the term trigger about the RDBMS.

It is a stored procedure that acts as soon as some event occurs. The programmers do not call events but are invoked automatically as soon as edits are made systematically.

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Q10). What is a VIEW, and how will you define it?

A “view” is a subset of a database used to retrieve, delete, or combine the data. As soon as you edit a view, the original data also changes in the table. Find out the difference between tables vs. views in SQL by clicking here. 

Q11). Do you have any idea of INDEX storage in RDBMS?

For creating pointers to the data, SQL server indexes are used. They help in finding rows in a table quickly. Indexes can be defined for multiple columns together with a different name. Users cannot see or access them but helps improve the database performance. For small tables, impacts can be negligible. In the case of complex data tables, the impact of indices is clearly visible.

Q12). There are two types of indexes in RDBMS. Can you tell me their names and their significance?

Yes, there are two methods for index storage in RDBMS. These are given below.

• Clustered Indexes
• Non-clustered Indexes

Clustered indexes can give information about the physical storage of the data and non-clustered indexes will give you an idea of logical ordering. Read an all-inclusive guide on the difference between clustered vs non-clustered indexes.

Q13). How is RDBMS a preferable option over DBMS?

It minimizes redundancy, and integrity can be maintained. It maintains data consistency and allows data sharing with other databases. It follows a set of rules to satisfy storage standards and maintains security.

Q14). Tell me about the buffer manager.

A buffer manager in database management system is responsible for allocating buffer space in the main memory in order to store temporary data. It transfers the data from third-party storage devices to the memory and puts some data into the cache for easy access. 

The buffer manager transfers the block address when a user requests specific data and the data block is available in the table buffer in the primary memory. 

Q15). Tell me about Keys and how they are valuable.

A key is a constraint added to a database to restrict data access requirements. These are important for any database to maintain maximum data integrity.

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Q16). How many keys can be applied to a database?

Different types of keys can be applied to databases as needed. Here we have listed the names of popular ones that are used frequently.

• Primary Key
• Candidate Key
• Super Key
• Foreign Key

Q17). What is the most common key that can be applied to almost all databases.

One of the most common key that could be applied to almost all databases is called a Primary Key and there is only one Primary key in one table. Primary key is an unique identifier like driver license number, or phone no. together with area code, etc. A RDBMS should have just one primary key. 

Q18). If multiple columns have to be used as a Primary key, what is it called?

When you want to use multiple columns as a primary key, then it is called a Candidate Key. Here’s a comprehensive guide on what is SQL candidate key. In a table a composite key is a candidate key which contains 2 or more attributes, i.e., columns that simultaneously identifies a table row or an entity’s occurrence. 

On the contrary, a compound key is a composite key for which every attribute that forms a key is a foreign key distinctly. 

Q19). If we are using the Primary key from any other table, then what is it called?

When you’re using a primary key from any other table, then it is called a Foreign key, and it is used to maintain referential Integrity. A foreign key is a column or a set of columns utilized to develop a link between the data in 2 database tables to monitor the data that could be saved in a foreign key database. 

Q20). What are the drawbacks of using a File Processing System?

The following are the drawbacks of the File Processing System:

• Inconsistency and redundancy of data
• Data access is difficult.
• Isolation of data
• Data security.
• It is not feasible to have concurrent access.
• Issues with security.

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Q21). What Do The "Integrity Rules" Mean?

Database integrity is determined by two rules. 

• The entity integrity states, "The value of the primary key cannot be NULL".
• Referential Integrity states, "The Foreign Key value can either be NULL or the Primary Key value of another relation.”

Q22). What's the difference between extension and intention?

The number of tuples in a table at any time is an extension. This is time sensitive. Intention is a constant value that specifies the table's name, structure, and restrictions.

Q23). How would you describe System R and its subsystems?

It is a prototype, and its goal was to show that a Relational System can be built that can be used in a real-world setting to address real-world issues, with a performance at least equivalent to that of existing systems.

It has two subsystems. They are

• Research Storage and 
• System Relational Data System

Q24). What is the difference between the data structure of System R and Relational Structure?

• Domains aren't supported.
• It is optional to enforce candidate key uniqueness.
• It is optional to enforce entity integrity.
• There is no requirement for referential integrity.

Q25). How can you tell the difference between logical and physical data independence?

Physical Data Independence defines that Physical data changes should not influence logical data. Whereas logical data independence defines that modifications at the logical level should have an impact on the view level.

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Q26).  How can you distinguish between ELT and ETL in DBMS?

Data is processed by ETL on a separate server, whereas ELT processes data within the data warehouse. Raw data is not moved into the data warehouse via ETL; instead, raw data is sent directly to the data warehouse using ELT.

Q27). How do you define an Object Oriented Model in a database management system?

The foundation of this concept is a collection of objects. Within an object, values are stored in instance variables. A collection of code that operates on an object is also known as an object. Certain sections of code are referred to as methods.

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Q28). Distinguish between an entity type and an entity set.

An entity type is a group of things with similar attributes. Whereas, an entity set is a collection of all entities in the database that belong to a specific entity type.

Q29). How can you define the degree of a relation?

The degree of a relation is defined as the no of occurrences in 1 entity which is related to no of occurrences in another entity. The following are the 3 degrees of relationships: 

• One-to-one relationship (1:1)
• One-to-many relationship (1:M)
• many-to-many relationship (M : N)

Q30). Describe the Record at a time procedure.

Each record from a group of records can be specified and retrieved using Low Level or Procedural DML. Record-at-a-time retrieval is the name for this method.

Q31). Define the Set-at-a-time procedure.

The High level or Non-procedural DML can define and retrieve several records in a single DML statement. This type of record retrieval is known as Set-at-a-time or Set-oriented.

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Q32). How can you distinguish between Relational Algebra and Relational Calculus?

Relational algebra uses procedural query language. It comprises a collection of procedures that accept one or two relations as input and output a new one. Whereas relational calculus is particularly optimized for relational databases. 

Q33). How do you define functional dependency?

X Y indicates a functional dependency between two sets of attributes X and Y that are subsets of R, and it constrains the potential tuple that could result in a R relation state r.

The restriction is that if t1[X] = t2[X], then t1[Y] = t2[Y] for any two tuples t1 and t2 in r. This means that the value of the X component of a tuple determines the value of the Y component.

Q34). Under what condition Functional Dependency F is said to be minimal?

In F, each right-hand side dependency has just one attribute.

We can't replace any dependency X A in F with a dependency Y A and still have a collection of dependencies identical to F. We can't remove any of F's dependencies while maintaining an identical set of dependencies.

Q35). Explain what a multivalued dependency is.

The constraint on any relation r of R is described by the multivalued dependence represented by X Y stated on relation schema R, where X and Y are both subsets of R: If two tuples t1 and t2 exist in r with the attributes t1[X] = t2[X], then t3 and t4 should likewise exist in r with the properties t1[X] = t2[X].

Q36). What do you understand by Lossless Join Property?

It ensures that misleading tuple formation does not occur with relation schemas after decomposition.

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Q37). How can you describe Fully Functional Dependency?

It is based on the concept of total functional dependency, in which the dependent attributes are evaluated by the deciding attributes. If removing any attribute A from X causes the dependency to break, it is called a fully functional dependency.

Q38). What exactly is BCNF?

A relation schema R is in BCNF if it is in 3NF and meets the extra restriction that X must be a candidate key for every FD X A.

Q39). In what conditions a relation schema is in 3NF?

A relational model R is in 3NF if it is in 2NF, and one of the following is true for every FD X A.

• R's Super-key is X.
•  R's most significant feature is A.
• If the primary key is transitively dependent on all non-prime attributes.

For more clarity, learn about database normalization 1NF, 2NF, 3NF, 4NF forms. 

Q40). Explain Domain Key Natural Form.

The relation is considered to be in DKNF if all constraints and dependencies that should hold on the constraint can be enforced by merely imposing the domain constraint and key constraint on the relation.

Q41). Explain what partial, alternative, artificial, natural, and compound keys are.

A partial key is a set of qualities that may be used to distinguish weak entities belonging to the same owner.

An Alternate Key is a Candidate Key other than the Primary Key. There are different types of SQL keys and their examples and uses. You must know how to use them in database applications.

• Artificial Key: If there is no evident key, either standalone or compound, the final recourse is to invent one by giving a unique number to each record or occurrence. This is called as creating an artificial key.
• Compound Key: When no single data element can uniquely identify occurrences inside a build, a compound key is formed by combining many components to create a unique identifier for the construct.
• Natural Key: When one of the data items included within a construct is utilized as the main key, the natural key is used.

Q42). Define Query Optimization.

Query optimization is the process of determining an efficient execution plan for assessing a query with the lowest estimated cost. The aim of query optimization is to identify a plan of execution that minimizes the time needed to process a query.

Q43). Define Checkpoint in DBMS.

A checkpoint is a snapshot of the database management system's current state. By employing checkpoints, DBMS can reduce the amount of work required upon restart in the event of many crashes.

Q44). What do you understand about transparent database management systems?

It means a database management system should provide a transparent distribution to the user. In other words, a transparent DBMS keeps the data hidden from the user. There are 4 kinds of database transparencies: distribution, translation, performance and DBMS transparency. 

Q45). Explain the Network and Hierarchical Schemas in Database Management Systems.

The Hierarchical Schema utilizes a tree-like structure to arrange data. Here are the components of a hierarchical model:

• It consists of nodes connected by branches.
• The root node is the highest node in the tree.
• When many nodes emerge at the top level, these are called root segments.
• There is only one parent for each node.
• A parent may have several children.

Network Schema - 

Network Schema is the hierarchical data model in its advanced form. It organizes data using directed graphs rather than a tree structure. A child can have more than one parent in this situation. It makes use of the two data structures known as Records and Sets.

The above figures can differentiate between hierarchical and network schema in DBMS.

Q46). Describe correlated subquery in DBMS.

For each row of an outer query, these are SQL subqueries that run. Each subquery is done just once for each row in the outer query.

A correlated subquery in a database management system is a subquery that applies to a database column that is not in the “FROM” clause. This database column could be in the Projection clause or inside the WHERE clause. Mostly, correlated sub-queries decline performance.

Q47). Differentiate between hash join and merge join 

When the projections of the connected tables are ordered on the join columns, a merge join is used. Hash joins are slower and consume more memory than merge joins. A hash join is used when the projections of the connected tables are not already sorted on the join columns.

Q48). How can you define a Deadlock condition? 

Deadlock happens when two transactions wait for a locked resource or while another transaction is held. Deadlocks can be avoided by enabling all transactions to acquire all locks at the same time.

Q49). Distinguish between A super key and a candidate key

A super key is a single key or a set of keys that helps identify a table record. Super keys can have one or more properties, even if all of them aren't required for the records to be identified. A candidate key is a subset of a Super Key that can identify records in a database using one or more attributes.

RDBMS Intermediate Interview Questions

When preparing for RDBMS job interviews, one of the most prominent ways to maximize your chances of cracking the interview is anticipating RDBMS questions and answers. 

Let’s examine the most frequently asked RDBMS intermediate-level interview questions and answers. 

Q50). What are the various JOIN operations in SQL?

There are different types of SQL joins. The logical operation JOIN is used to get data from many tables. Only when there is a logical link between two tables can it be used? Moreover, the JOIN operator uses data from one table to extract data from another.

Also, gain comprehensive knowledge about SQL Schema and find out how to create, alter and drop a schema in SQL.

RDBMS Interview Questions and Answers for Experienced

Running through the highly awaited REDBMS interview questions is important for cracking your interview and determining your existing preparation. Also, in-depth knowledge of RDBMS opens doors to a lot of job opportunities in top MNCs like Pioneer, Bank of America, IBM, Accenture, and so on.  So let’s get started with the next section, where we’ve shared interview questions in RDBMS.

The list of RDBMS interview questions and answers for experienced candidates. 

Q51). What is a Database?

A database is a logical, organized, and consistent collection of data that can be easily accessed, managed, as well as managed. It is designed to let you create, insert and update the data efficiently. Database mostly contains objects and tables, including records and fields. 

Q52).  Database Design Interview Questions: What is RDBMS? How is it different from DBMS?

The abbreviation of Relational Database Management Systems, RDBMS, helps maintain table data records and indices. It is the form of DBMS that utilizes the structure to find and access data concerning the other pieces of data in the database.   RDBMS is basically a system that allows you to perform numerous operations like update, insert, delete, manipulate, and administrator a relational database with minimal difficulties. 

Q53). Database Questions: What are the different features of an RDBMS?

Name: Every relation in a relational database should contain a unique name. 

Attributes: Each column in a relation is called an attribute. 

Tuples: Each and every row in a relation is called a tuple. It also presents a collection of attribute values. 

Q54). Questions about Databases: What are the advantages of RDBMS?

Here is the list of major advantages of RDBMS:

• It controls redundancy. 
• It can share data. 
• It can enforce integrity. 
• It can avoid inconsistencies. 

Q55). Explain the different languages present in DBMS.

Here is the list of different languages present in DBMS:

DDL: DDL stands for Data Definition Language; it contains commands required to define the database.

DML: Data Manipulation Language contains commands required to manipulate the data available in the database. 

Learn in-depth about the different types of SQL server operators through this video:

TCL: TCL or Transaction Control Language contains commands required to deal with the database transaction. 

DCL: Standing for Data Control Language, DCL contains commands required to deal with the user permission and controls of the database. 

Q56). What is an Index? Explain its different types.

An index is a performance-tuning method that allows the faster retrieval of records from the table. An Index helps in creating an entry for every value. There are three types of SQL server indexes: 

Unique Index: Unique index is applied automatically when the primary key is defined. It does not let the field get duplicate values. 

Clustered Index: Clustered Index reorders the physical order of the table and searches depending on the key values. This type of index can have just one clustered index. 

NonClustered Index: It does not modify the physical order of the table and maintains the logical order of data. Each table can have 999 nonclustered indexes. 

Q57). What is Database partitioning?

Database partitioning is about partitioning tables and indexing them into smaller pieces to maintain and access the data at a better level. So, does table partitioning improve the performance of SQL servers? Yes! This process decreases the price of storing a huge amount of data and improves performance and manageability. 

Q58). Explain the Data Dictionary.

It is a set of information explaining the content and structure of the tables and database objects. This information controls, manipulates, and access the relationship between database elements. 

Q59). What do you understand about Database Triggers?

Database Trigger is a set of commands that get executed when an event such as Before Insert, After Insert, On Update, and On Delete of row occurs in a table. 

Q60). Explain Codd’s 12 rules for an RDBMS.

An entity can be taken as an object or thing with independent existence. An entity set is a collection of all entities within a database. Sometimes, if an entity set does not have all the necessary attributes to define key constraints and other logical relationships, then it is termed as a weak entity set. If an entity set has all the necessary attributes to define the primary key and other constraints, it is termed a strong entity set.

Q61). What do you understand by the terms like DDL, VDL, SDL, and DSDL in RDMS? 

• DDL can be defined as the database schema that specifies a set of definitions through a special language called DDL.
• VDL gives information about views and their mapping with the conceptual schema.
• SDL gives information about the internal schema and defines the relationship among two storage schemas.
• DSDL defines the storage structures or access methods utilized by databases.

Q62). What are the different relational operators that can be applied to a database?

A wider range of relational operators that can be applied to a database can be given as: SQL Server operators.

• A Union operator is used to combine multiple rows to avoid duplicate content.
• An intersect operator is used for finding common elements within a row.
• A Cartesian operator is used as a cross-join operator to apply on two relations.
• A difference operator is used to identify the different values in multiple rows.

Q63). What is the significance of ACID properties for a database?

1. Atomicity
2. Consistency
3. Isolation
4. Durability

These four properties are considered highly important for any database. These properties make a database easy to access and use. It is possible to share data among tables conveniently. Also, it focuses on data accuracy and avoids redundancy.

Q64). How are DBMS and RDBMS different from each other? Give some meaningful differences.

DBMS tells about data storage and data creation. RDBMS explains relations among tables and data values. DBMS operations can be used for a specific database, but RDBMS can work on multiple databases together. Find more points of differences in how to differentiate between DBMS and RDBMS.  

Q65). When designing a database, how many relationships can you define?

When designing a database, three types of relationships can be defined. These are:

1. One to One
2. One to Many
3. Many to Many

Q66). As we know, there are various normalization forms. So, can you explain the difference between 4NF and 5NF?

In the 4NF, it should satisfy the 3NF and not contain two or more views about an entity. In the 5NF, we can reconstruct the information from small pieces of content so that they can be maintained with maximum consistency. 

Q67). One of system architects' biggest challenges is delivering maximum throughput so that millions of transactions can be exceeded per second. So, how will you handle this challenge with care? Justify your answer based on your previous work experience.

Whenever you are working on big data problems, it should be handled with care. Let us understand the concept with three technical terms Data Ingestion, Transformations, Storage & Analytics.

Data Ingestion uses technologies like Apache Kafka and gracefully streamlines the data across different targets. The second term is transformation, where data is reconstructed and transformed into a meaningful real-time solution.

The last term is Storage & analytics, where No SQL database can be utilized to manage all data issues and works on consistency problems eventually. Once you are done with it, these three features can give you more flexibility, high throughput, and low-latency benefits. In brief, we should replace the traditional batch-oriented approach with modern streaming solutions. If you are a beginner, then you can learn more about No SQL through a comprehensive No SQL tutorial for beginners. 

Q68). How can views be named as Data independence standards?

A “view” is defined as a subset of a database or tables stored in it. It can be used to retrieve, delete, or combine the data. Each View can be taken as a separate table and accessed for the application. When changes are made to a specific VIEW, it will not impact others. This is the reason why VIEWS should be learned first to understand the concept of Data Independence in detail.

Q69). What is a Weak and Strong Entity Set according to your past experiences?

An entity can be taken as an object or thing with independent existence. An entity set is a collection of all entities within a database. Sometimes, if an entity set does not have all the necessary attributes to define key constraints and other logical relationships, then it is termed a weak entity set. If an entity set has all the necessary attributes to define the primary key and other constraints, it is termed a strong entity set.

Q70). Explain the terms ‘Record’, ‘Field’, and ‘Table’ in terms of database.

• Record: It refers to a collection of values of a specific entity. 
• Field: This is an area within a record which is reserved for specific data. 
• Table: This is also a collection of records but specific types. 

Q71). What is the difference between Cluster and Non-Cluster Index?

There is a major difference between cluster and non-cluster indexes. Clustered indexes make changes in the table and reorder how records are stored there. Nonclustered indexes also make changes in the data stored in the tablet, but it makes a completely different object within the table. 

Q72). What do you understand by ‘Atomicity’ and ‘Aggregation’? 

Atomicity is the condition where all the transaction's actions are performed or none. This means if there is an incomplete transaction, the DBMS will undo the pending transactions' impacts. 

Aggregation: It expresses the relationship with the entities’ collection and their relationship. 

Q73). What are all types of user-defined functions?

There are three types of user-defined functions. 

• Scalar Functions in SQL
• Inline Tablet value Functions 
• Multi-Statement Valued Functions 

 Q74). What is Online Transaction Processing (OLTP)?

OLTP is used to manage transaction-based applications; it is used for data entry, data retrieval, and data processing. It makes data management efficient. The purpose of the OLTP system is to serve real-time transactions. 

Q75). Name the different data models that are available for database systems.

Here is the list of three different data models that are available for database systems: 

• Relational Model
• Network Model
• Hierarchical Model

Q76). What are Union, minus, and Interact commands?

Union: It combines the outputs of two tables, eliminating the duplicate rows from the tables. Use SQL union all operators. 

Minus: It returns rows from the first query but not from the second query. When you match records of the first and the second query and other rows, you can see the query as a result set. 

Intersect: It is used to return rows that both queries return.  

Q77).  Explain character manipulation functions. Explains its different types in SQL.

Character manipulation functions effectively extract, edit, format, or modify in some way a character string. Character manipulation functions can be used to manipulate char. Strings. Different types of character manipulation functions are as follows:

CONCAT, SUBSTR, INSTR, LPAd, RPAD, TRIM and REPLACE.

Different types of SQL:

Trim: The SQL trim helps to get rid of the leading and trailing characters from a character string. Learn more about what is the order of operation with LTRIM/RTRIM/ISNULL in SQL server. 

Translate: Translate replaces a sequence of characters in a string with another sequence of characters. It replaces one character at a time. 

Q78). Explain the Primary Key and Composite Key.

The primary key is the combination of fields that uniquely specify a row. It is a unique key that has an implicit NOT NULL constraint. It means its values cannot be NULL.

The form of the candidate key is referred to as a composite key, a set of columns that uniquely figure out every brown in the tablet.  

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Q79). What do you mean by cardinality and its types?

Cardinality is defined as its equivalence class under equinumerosity. Simply, it is described as a fundamental relationship between two entities or objects. There are three types of cardinalities- one-to-one, one-to-many, and many-to-many.   

Q80). What do you understand about B-Trees?

It basically represents the data structure in the form of a tree for external memory that reads and writes large data blocks. It is generally used in databases and file systems where all the insertions, deletions, sorting, etc., are done in logarithmic time.

Q81). Explain the functionality of the DML Compiler.

The work of a DML compiler is to convert the DML statements into a query language that the query evaluation engineer can understand and process. The DML Compiler is needed since the DML is a family of syntax elements that are quite similar to the other programming language that needs compilation. That is why compiling the code in a language the query evaluation engine can understand is important. 

Q82). How can you distinguish between OLAP and OLTP?

Online transaction processing is referred to as OLTP, whereas online analytical processing is called OLAP. OLTP stands for online database modification, while OLAP stands for online database query response.

Q83). What is the use of the NVL() function?

Null values can be replaced with default values using the NVL function. If the first parameter is null, the function returns the second parameter's value. If the first parameter is anything other than null, it is ignored. This function is only accessible in Oracle; SQL and MySQL are not supported. 

Check out our top SQL server interview questions and answers to prepare well for your upcoming SQL developer interviews.

Q84). Distinguish between Rank() and DenseRank().

Here are the differences between DENSE_RANK vs RANK functions in SQL. 

The rank of each row within your sorted partition is determined by the RANK() function in the result set. The DENSE RANK() method assigns a unique rank to each row inside a partition based on the provided column value, with no gaps. 

Q85). What do you understand by NoSQL?

NoSQL databases are designed for certain data models, such as graphs, documents, key-pairs, and wide-column tables. Unlike relational databases, they feature flexible schemas. NoSQL databases are popular because of their ease of use, functionality, and scalability. Unlike SQL databases, they can be expanded horizontally across hundreds or thousands of servers.

Did Al set to grow in SQL? To help you navigate through the journey successfully, here is a guide on How to Become a SQL Professional. 

Q86). What do you understand by Concurrency Control?

Concurrency control is a database management system process that ensures that concurrent activities do not clash.

Q87). What are various database locks and their types?

Locks are commonly used to ensure that only one user/session can modify a certain piece of data.

There are different types of database locks: 

• Shared Lock - When a request for a shared lock on a table is approved, the table becomes read-only. Other read operations can share this lock, allowing them to read the table simultaneously.
• Exclusive Lock - When an operation seeks an exclusive lock on a table, and it is granted, it has exclusive permission to write to the table. Other activities will be prevented if they request access to the locked table.

Q88). What do you understand by Data Warehousing?

Data Warehouse is the process of gathering data from several sources (extracting, converting, and loading) and storing it in a single database. The data warehouse can be considered a central repository where data flows from transactional systems and other relational databases.

Q89). What do you understand by lock escalation?

Lock escalation occurs when a system combines numerous locks into a single higher-level lock, usually to free up resources taken up by many fine-grained locks.

Q90). What do you understand by lock contention?

Lock contention arises when numerous operations request an exclusive lock on the same table. Operations must wait in a queue in this situation. If you have ongoing lock contention, you must divide those data blocks further so multiple processes can gain exclusive lock simultaneously.

Q91). What do you understand by hashing, and what are its advantages?

Hashing is a search method. A method of mapping keys to values. Hash functions take a string of characters and turn it into a fixed-length value that may be used as an index to find the original element.

Advantages of hashing

• It can be used to index and retrieve entries from a database in real-time, which is quicker than conventional search methods.
• It is an ideal data structure for point look-up.

Q92). What are the best practices to improve query performance?

• The best practices to improve query performance are:
• Multiple joins in a single query should be avoided.
• Instead of using sub-queries, use joins.
• For regularly used data and more complicated searches, utilize stored procedures.
• To limit the size of your results, use WHERE expressions.

Q93). What do you understand by the term ‘Write Ahead Log’ in DBMS?

The Write Ahead Log is a database system approach for maintaining the atomicity and durability of writes. The WAL's main principle is that before we make any actual changes to the database state, we must first log the whole set of activities we want to be atomic and durable for storage.

Q94). What does ALIAS stand for? 

A table or column may be given an ALIAS name. Use this alias name in the WHERE clause to identify the table or column. Aliases are put to use in order to assign a table, or a column, a temporary name. They’re usually used for making column names more eBay to read. 

Alias exists only for till the duration of that SQL query. 

Q95). What do Scalar and Aggregate Functions do? 

To assess mathematical calculations and return single values, we employ aggregate functions. From a table's columns, one can compute this. Based on the input value, scalar functions return a single value.

Q96). Define Phantom Deadlock.

Phantom deadlock detection refers to the situation when a deadlock does not actually exist but is still detected by deadlock detection techniques as a result of a delay in the propagation of local information.

Q97). What is a Checkpoint?

The inconsistent state is before the checkpoint, which is the point at which all the logs are permanently recorded on the storage drive. The system can restart from the checkpoint in the event of crashes, saving time and effort.

Q98). What is Database Partitioning?

Database partitioning, or data partitioning, applies to the process of breaking the data present in the application’s table into distinct partitions. You can easily store, manage and access these data partitions independently. 

In order to manage and access the data at a finer level, database partitioning involves dividing tables and indexes into smaller sections. Here‘s a guide on how to order and partition by multiple columns. 

Q99). Why is Database Partitioning Important?

• The benefits of database splitting include increased manageability and query performance.
• It makes routine administrative duties easier.
• It serves as a vital building block for systems with very high availability needs.
• It enables access to a significant portion of a single partition.

Q100). Establish stored procedures.

A stored procedure is a group of pre-compiled SQL queries that, when run, represent a program that accepts input, processes it, and outputs the results.

In other words, a stored procedure is a group of SQL statements with allocated name, that are saved in a RDBMS as a set, so that it could be recycled and shared using several programs. 

Q101). Explain the differences between the commands “DELETE,” “TRUNCATE,” and “DROP.”

The data can be recovered using the COMMIT and ROLLBACK statements after running the "DELETE" action.

Following the completion of the "TRUNCATE" operation, the statements "COMMIT" and "ROLLBACK" cannot be used to recover the deleted data.

Use the' DROP' command to remove a table or key, such as the primary key or foreign key. Find more points of difference between DELETE vs TRUNCATE SQL here. 

Q102). What is black box testing for databases?  

A software testing technique called "black box testing" involves testing the functionality of software programs without being aware of the internal code structure, implementation specifics, or internal paths. Black Box Testing is a sort of software testing that is only motivated by software requirements and specifications and focuses on the input and output of software applications. An alternative term for it is behavioral testing.

Q103). Why is Oracle the most popular relational database?

Relational databases interview questions frequently include Oracle because it is the most widely used RDBMS. Its fully scalable relational database architecture accounts for its popularity. Oracle database products provide customers with versions that are both high-performing and economical.

The Oracle database provides a built-in network component that enables network communications. As a result, it has become the preferred option for leading international corporations that manage and process data across wide and local area networks.

Q104). Recursive stored procedure: what is it?

A stored process that continuously invokes itself until it encounters a boundary condition Programmers can reuse the same code multiple times thanks to this recursive function or process.

Q105). What kinds of collation sensitivity are there?

The following is a list of collation sensitivity variations.

• Case Sensitivity: A, A, and B, B
• Accent Perception.
• Japanese Kana characters, or Kana Sensitivity.
• Single-byte and double-byte characters that are sensitive to width.

Q106). What are local and global variables and their differences?

Local variables are those that can be utilized or already exist within a function. They cannot be referred to or used since the other functions are unaware of them. Every time that function is invoked, variables can be created. 

The variables that can be used or are present throughout the entire program are known as global variables. No two variables that have been declared globally may be utilized in functions. When that function is called repeatedly, global variables cannot be generated.

Q107). What are Constraints?

SQL constraints are used to limit the table's data type options. It can be supplied when the table statement is being created or modified. The list of restrictions includes UNIQUE PRIMARY KEY FOREIGN KEY, NOT NULL CHECK BY DEFAULT

Q108). How are views and data independence related?

The view is a fictitious table kept active so that users can view their data even if it doesn't exist.

• It comes from the fundamental table. The view directly reflects the file and is kept in the data dictionary.
• Views do not reflect base table updating or reconstruction.
• As it occurs at the logical level and not the physical level, it is related to logical data independence.

Q109). What is 1NF in the DBMS?

1NF is known as the First Normal Form.

The domain of an attribute should only have atomic values in this kind of normalization, which is the simplest. The purpose of this is to eliminate any duplicate columns from the table.

Q110). What does a SQL CLAUSE mean?

This is a crucial RDBMS questions and answers. 

This is used in conjunction with SQL queries to retrieve specified data based on user requirements and SQL-defined constraints. This is particularly useful for selecting specific records from the entire set of records. Find more information about SQL having clause functions to learn more about SQL clauses. 

Q111). What are the uses of DBMS?

Following are some of the uses of DBMS: 

• Authentication and authorization configuration. 
• Simple to set up user accounts, mention access policies, and change limitations and access scopes.
• Offers data backups.
• Performance tuning.
• Data recovery.

Q112). What are RDBMS examples? And main components of REDBMS

A few examples of RDBMS include - Oracle, Microsoft SQLServer, MySQL, and PostgreSQL. RDBMS consists of numerous components like - tables, records, attributes, instances, schemas, keys, etc. 

Q113). What is the difference between Extension and Intention?

• Extension - Refers to the total no of tuples in a database at any given time and completely dependent on the time.
• Intension - It doesn’t depend on the time and explains the database’s name, configuration, and restrictions. 

Q114). What is a Buffer Manager in RDBMS?

In a relational database management system, a buffer manager enables relational tasks, heap files, access methods to read/write, allocate and de-allocate pages, etc. These tasks are performed on disc pages by fundamental database class objects, which the buffer manager appeals to.

Q115). Describe a NULL Value.

Understanding the dissimilarities between NULL and other values, like zero or fields with spaces. In a database, a NULL value is in a field containing no values. At the time of constructing a record, a field with a NULL value shows that it is empty. 

Q116). Describe The Three Levels Of Data Abstraction.

There are 3 levels of data abstraction:

• Physical level: The lowest level of data abstraction explains how data gets stored.
• Logical level: The next higher level of data abstraction explains what data is stored in the table and what is the relationship between that data.
• View level: The highest level of data abstraction explains just part of the complete database.

Q117). What Is E-r Model?

This is one of the most commonly asked RDBMS  important questions. 

The e-r model is dependent on the real world that contains fundamental objects referred to a entities and of the relationship between them. Entities are explained in a table by using a group of attributes. 

Check Out Other Data Management Courses Offered by JanBask Training:

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Final Words:

These Oracle RDBMS interview questions are designed as per the protocol of Oracle Inc.

The blog gives you a sound idea of RDBMS interview questions and answers that you may encounter in your next interview. The discussion during interview questions on RDBMS always starts with basics like RDBMS, Normalization, Triggers, Views, etc. After this, the interviewer will check your practical knowledge through different examples. So, the blog is enough to practice theoretical RDBMS concepts. To learn the practical aspects of RDBMS and how it is used by Companies, join our online SQL server training program to master the concepts of databases from scratch! At JanBask Training, and start exploring the world-class RDBMS systems now.

FAQs

Q1. What is the difference between DBMS and RDBMS?

Ans:- DBMS stands for Database Management System, and RDBMS stands for Relational Database Management System. RDBMS stores data in tables, whereas DBMS stores data as a file.

Q2. What is SQL in RDBMS?

Ans:-  SQL is a standard database language, i.e., Structured Query Language in RDBMS which is used to create, update, and retrieve data. 

Q3. What are the Types of DBMS?

Ans:-  Following are the types of DBMS:

• Hierarchical Database
• Network DBMS
• Relational DBMS
• Object-Oriented Relational DBMS

Q4. What are the Main Components of RDBMS?

Ans:-  An RDBMS comprises several components like - tables, records, attributes, instances, schemas, keys, etc., which create a relational database.

Q5. What does RDBMS offer the Functions?

Ans:-  RDBMS offers 4 major functions as follows −

• Security
• Accuracy
• Integrity
• Consistency

Q6. What are RDBMS examples?

Ans:-  A few examples of RDBMS are- Oracle, Microsoft SQLServer, MySQL, and PostgreSQL.

Q7. What is the objective of the online SQL server training?

Ans:-  The major objective of our online SQL server training is to offer an SQL online course that provides the experience same as offline classrooms and saves students time traveling to the physical classes, including their finances, energy & time.

Q8. What skills will I learn through this online SQL server training?

Ans:-  Following are the important skills you’ll learn through our comprehensive data management courses. 

• SQL Server, DDL, DML
• SQL Server Programming, Indexes, Functions
• SSIS Package Development and Deployment Procedures
• SSRS Report Design
• Formatting SSRS Report & Models
• Building SSAS Cubes, Power BI

Q9. What all topics will be covered in the beginner’s level online SQL server training?

Ans:-  Our online SQL server training covers topics from the basics of the SQL discipline to the advanced level.  The instructors will teach the following theoretical SQL concepts at the beginner level.

SQL Server, DDL, DML

• What is Structured Query Language, Version,
• SQL architecture, client/server relation, and database types
• Installations process
• Transaction logs-ldf, MDF and ndf files
• Different types of data types
• What is a database, table, Key factors to create databases/tables?
• DDL, DML, DCL and TCL statements
• Insert record/data in tables
• Modify/Update the existing data.
• SQL Server Operators, Normalisation, and much more.

Q10. Can I get a free demo class?

Ans:- In order to present you with a quick roadmap of our online SQL server training program, we do provide a free demo class. The goal of this class is to make you familiar with everything that we’ll cover in our course. 

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