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With the advent of a monumental shift towards using database management systems, the demand for individuals who can control those databases has skyrocketed. This has given an excellent boost to the demand for SQL Server professionals, especially with SQL Server Training in the job market. Many companies are on a constant lookout for SQL Server professionals to meet the needs of their database management system. In this blog, we have tried to help all the aspirants of SQL server jobs as well as SQL server enthusiasts to sharpen up their knowledge of the SQL server with a list of top 151+ SQL interview questions.
Here are some of the most frequently asked questions in the field of SQL Server. The best part is that we have even categorized them into various popular subdivisions in the field of SQL such as MySQL, SQL PL, Oracle, etc. Enjoy reading!
Q1). Which is the latest version of SQL Server and when it is released?
SQL Server 2017 and the release date of its CU was 25.03.2019
Q2). What is it that the SQL Server is mainly used for?
SQL Server is one of the most prominent Relational Database Management Systems. This is a product from Microsoft to store and deal with the data in a database.
Q3). Which language does the SQL Server support?
SQL Server depends on the execution of the SQL which is also called Structured Query Language to work with the information inside the database. These kinds of SQL tutorial for beginners can help you learn such basic topics.
Q4). Which TCP/IP port does the SQL Server primarily runs on?
By default, the SQL Server runs on port 1433.
Q5). Name the different types of index configurations possible for a SQL table?
This is how you should answer these kinds of SQL interview questions. The SQL table can have any one of the following index configurations-
Q6). What is the recovery model?
Recovery model fundamentally discloses to SQL Server what information ought to be kept in the exchange log record and for to what extent.
Q7). What is a FULL Back up in SQL environment?
A full backup is the most widely recognized kind of reinforcement in SQL Server. This is the finished backup of the database. It additionally contains some portion of exchange log so it very well may be recovered.
Q8). When is the UPDATE_STATISTICS command used?
This is how you should answer these kinds of SQL interview questions. As the name infers UPDATE_STATISTICS command refreshes the measurements utilized by the file to make the search simpler.
Q9). What is Mirroring?
Mirroring is a high accessibility arrangement. It is intended to keep up a hot reserve server which is predictable with the essential server as far as an exchange. Exchange Log records are sent legitimately from a central server to an auxiliary server which stays up with the latest with the primary server. Include these major SQL topics in your preparation list to be prepared for all types of SQL questions interview.
Q10). Is it possible to take the full database backup in Log shipping?
Truly, we can take the full database reinforcement. It won't influence the log shipping. When you are looking to prepare for a SQL interview, make sure not to miss these kinds of SQL test interview questions.
Q11). How can you check the SQL Server version?
SQL Server version can be checked by running the following command- SELECT @@Version
Q12). What do you understand the PRIMARY KEY?
The primary key is a section whose qualities extraordinarily distinguish each column in a table. Primary key qualities can never be reused.
Q13). What is a heap?
A heap is a table that does not contain any clustered file or non-clustered index. This is top SQL interview questions and answers, you should not miss.
Q14). List the different normalization forms?
15). Why is replication required on the SQL Server?
This is majorly used to expand the limit of the perusing and to give an alternative to its clients to choose among different distinctive servers to play out the read/compose operations.
Q16). What is a Database?
The database is an organized form of information for simple access, putting away, recovery and overseeing of information. This is otherwise called organized type of information which can be gotten to from multiple points of view.
Q17). What are the tables and Fields?
A table is a set of information that is sorted out in a model with Columns and Rows. Columns can be sorted as vertical, and Rows are horizontal. A table has indicated a number of sections that are called fields yet can have any number of columns which is called record. When you are looking to prepare for a SQL interview, make sure not to miss these kinds of frequently asked SQL test interview questions.
Q18). What is RDBMS?
RDBMS represents Relational Database Management System. RDBMS stores the information into the gathering of tables, which is connected by normal fields between the sections of the table. It likewise gives social administrators to control the information put away into the tables.
Q19). What are joins in SQL?
A JOIN clause is generally utilized to consolidate rows from at least two tables, in light of a related section between them. It is utilized to blend two tables or recover information from there.
Q20). What are Constraints?
Constraints are utilized to determine the point of confinement on the information kind of the table. It very well may be indicated while making or changing the table statement. When looking to attempt your interview at the first attempt, make sure to include such important SQL interview questions and answers.
Q21). Illustrate the difference between SQL and MySQL.
SQL is a standard language which represents Structured Query Language dependent on the English language though MySQL is a database management framework. SQL is the center of the social database which is utilized for getting to and overseeing database, MySQL is an RDMS (Relational Database Management System, for example, SQL Server, Informix and so on. This is one of the SQL basic interview questions you can't miss.
Q22). What do you understand by the term data integrity?
Data Integrity characterizes the precision just as the consistency of the data put away in a database. It additionally characterizes integrity limitations to authorize business controls on the information when it is gone into an application or a database. Go through such SQL topics once to ensure you have good commend on these basic SQL questions in interview.
Q23). Write a SQL query which is used to display the current date?
This is how you can answer these kinds of SQL interview questions when you are a fresher in the industry. In SQL, there is a work in capacity called GetDate() which restores the current timestamp/date.
Q24). What do you mean by Denormalization?
Denormalization refers to a strategy which is utilized to get to information from higher to bring down types of a database. It causes the database supervisors to expand the execution of the whole framework as it brings repetition into a table. It includes the excess information into a table by joining database questions that consolidate information from different tables into a solitary table. Candidates find these types of SQL common interview questions typical to answer, so you need to practice more.
Q25). Illustrate the difference between DROP and TRUNCATE commands?
DROP command evacuates a table and it can't be moved over from the database though TRUNCATE command expels every one of the rows from the table.
Q26). Do you think that NULL values are same as that of zero or a blank space?
No, A NULL value isn't at all equivalent as that of zero or a blank space. Null value speaks to a value which is inaccessible, obscure, allotted or not pertinent though zero is a number and blank space is a character. This is one of frequently asked SQL interview questions and answers, so invest some more time to practice such topics.
Q27). Illustrate the difference between cross join and natural join?
The cross join delivers the cross product or Cartesian result of two tables while the regular join depends on every one of the columns having a similar name and information types in both the tables.
Q28). What do you understand by a subquery in SQL?
A subquery is an inquiry inside another question where a query is characterized to recover information or data again from the database. In a subquery, the external question is called as the main query through the inner query is called subquery. Subqueries are constantly executed first and the consequence of the subquery is passed on to the principal inquiry. It very well may be settled inside a SELECT, UPDATE or some other question. A subquery in SQL can likewise utilize any correlation administrators, for example, >,. When you are looking to prepare for a SQL interview and crack it at your first attempt, make sure not to miss these kinds of SQL test interview questions.
Q29). What are the different operators available in SQL?
There are three kinds of SQL operators that are available in SQL, namely:
Q30). Why do you need group functions in SQL?
Group functions work with the set of rows and return one outcome for every given group. A portion of the generally utilized group functions is AVG, COUNT, MAX, MIN, SUM, VARIANCE.
Q31). What is normalization?
Standardization is the way toward limiting redundancy and dependency by sorting out fields and tables of a database. The fundamental point of Database Normalization is to include, erase or adjust the field that can be made in a solitary table. Candidates find these types of common SQL interview questions typical to answer, so you need to practice more to gain knowledge on it.
Q32). What is Index?
An index is acting tuning strategy for permitting quicker recovery of records from the table. A record makes a section for each esteem and it will be quicker to recover information.
Q33). What is a stored procedure?
Stored Procedure is a function comprised of numerous SQL explanation to get to the database framework. A few SQL proclamations are merged into a putaway strategy and executed them at whatever point and wherever required. This is one of the SQL basic interview questions you cannot afford to miss when you are looking for a career in SQL.
Q34). What is Datawarehouse?
The data warehouse is a focal vault of information from numerous wellsprings of data. That information is solidified, changed, and made accessible for mining and web-based handling. Stockroom information has a subset of information called Data Marts.
Q35). What are all types of user-defined functions?
Three types of user-defined functions are.
Candidates find these types of SQL common interview questions typical to answer, so you need to practice more to master in it.
Q36). What is the command to fetch common records from two tables?
Select studentID from student. INTERSECT Select StudentID from Exam
Q37). List out the ACID properties.
Following are the four properties of the ACID.
Q38). What are string functions used for in SQL?
In SQL, string capacities are utilized basically for the purpose of string manipulation
Include these major SQL topics in your preparation list to be prepared for all types of SQL questions interview.
Q39). What is Collation?
Collation is characterized as a lot of standards that decide how character information can be arranged just as thought about. Character information is arranged utilizing decides that characterize the right character grouping alongside choices for determining case-affectability, character width, highlight marks, kana character types. Go through such SQL topics once to ensure you have good commend on these basic SQL questions in interview.
Q40). What is a CLAUSE in SQL?
A SQL clause helps to restrain the outcome set by giving a condition to the question. A clause helps the columns from the whole arrangement of records. CLOUSE is a significant topic in SQL that makes that is why you must be prepared to answer such SQL interview questions and answers.
Q41). What do you infer by an ALIAS command?
ALIAS can be given to any table or a segment. This alias name can be alluded in WHERE condition to distinguish a specific table or a column. Include these kinds of SQL test interview questions in your preparation list whether you are a fresher or an expert professional.
Q42). What are the local variables?
These variables can be utilized or exist just inside the function. These variables are not utilized or referred by some other function.
Q43). What are the global variables?
This is how you should answer these kinds of SQL interview questions to ensure your instant success on this career path.
These factors are the factors which can be gotten to all throughout the program. Global variables can't be made at whatever point that function is called.
Q44). What is the syntax of STUFF function?
STUFF(string_expression,start, length, replacement_characters)
Q45). What is the need of the MERGE statement?
This statement allows conditional update or insertion of data into a table. It performs an UPDATE if a row exists, or an INSERT if the row does not exist.
Learn about SSAS to get a better understanding of SQL here are the Top 75 Interview Questions For SSAS.
Q46). What do you mean by a recursive stored procedure?
This is how you should answer these kinds of SQL interview questions and excel in the related topics.
Restrictive stored procedure refers to a stored procedure which calls by itself until it reaches some boundary condition. This recursive function or procedure helps the programmers to use the same set of code n number of times.
Q47). List the ways in which a Dynamic SQL can be executed?
A dynamic SQL can be executed in the following ways-
Candidates find these types of SQL common interview questions typical to answer, so you need to practice more to stay competitive.
Q48). What are the different types of joins in SQL?
The different kinds of SQL joins are-
Q49). What is identity in SQL?
An identity column in the SQL naturally creates numeric qualities. We can characterize a begin and addition estimation of the identity column. When you are looking for a bright career in SQL, make sure not to miss these kinds of significant SQL test interview questions.
Q50). Why MySQL is used?
MySQL database server is reliable, quick and simple to utilize. This product can be downloaded as freeware and can be downloaded from the web. Candidates find these types of common SQL interview questions typical to answer but you must not miss them.
Q51). What is the default port for MySQL Server?
Q52). How to represent ENUMs and SETs internally?
ENUMs and SETs are utilized to signify controls of two because of storage optimizations. This is one of frequently asked SQ interview questions and answers.
Q53). What storage engines are used in MySQL?
Storage engines are also called the table types. The data is stored in various files by way of several techniques. Go through such SQL topics once to ensure you have good commend on these basic SQL questions in interview.
Q54). What are the drivers in MySQL?
The drivers available in MySQL are:
Q55). What does myisamchk do?
t compresses the MyISAM tables, which in return decreases their disk or you can say the memory usage.
Q56). What are federated tables?
This is how you should answer these kinds of SQL interview questions and tackle all the questions related to such topics.
Federated tables are the tables that permit access to the tables located on the other databases located on other servers.
Q57). What, if a table has one column defined as TIMESTAMP?
Timestamp field is used to get the latest timestamp whenever a row is altered.
Q58). What is BLOB?
A BLOB in MySQL is a binary large object that can contain a variable amount of data in it. Candidates find these types of top SQL interview questions typical to answer, so you need to practice more.
Q59). How many types of BLON objects are there?
There are four types of BLOB –
Q60). What is PL SQL?
PL SQL is a procedural language which has intelligent SQL, just as procedural programming language builds like conditional branching and iteration.
Q61). Explain the uses of a cursor.
The cursor is a named private territory in SQL from which data can be gotten to. They are required to process each column independently for questions which return various lines.
Q62). What are the two types of exceptions?
The error handling part of PL/SQL square is called Exception. They have two sorts: user_defined and predefined.
Q63). Explain Raise_application_error.
It is a procedure of package DBMS_STANDARD that permits issuing of user_defined blunder messages from database trigger or put away sub-program.This is one of frequently asked SQL interview questions and answers.
Q64). Define Implicit Cursor.
A cursor is implicit by default. The client can't control or process the data in this cursor.
Q65). What are Explicit Cursors?
If a query returns numerous columns of information, the program characterizes an express cursor. This enables the application to process each column consecutively as the cursor returns it.
Q66). What is a mutating table error?
It happens when a trigger endeavors to refresh a column that it is as of now utilizing. It is fixed by utilizing perspectives or brief tables, so the database chooses one and updates the other. When you are looking to prepare for a SQL interview, make sure not to miss these kinds of major SQL test interview questions.
Q67). When is a declare statement required?
DECLARE statement is utilized by PL SQL mysterious squares, for example, non-put away methods. In the event that it is utilized, it must start things out in an independent document. Go through such SQL topics once to ensure you have good commend on these basic SQL questions in interview.
Q68). How many triggers can be applied to a table?
Q69). List the 3 basic parts of a trigger.
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Q70). What is an Intersect?
is the result of two tables and it records just coordinating rows.
Q71). What is the use of SYSDATE keyword?
SYSDATE alludes to the present server framework date. It is a pseudo column.
Q72). What does fetching a cursor do?
Fetching a cursor peruses ResultSet column by row.
Q73). What does closing a cursor do?
Closing a cursor clears the private SQL zone just as de-allots memory. This is one of frequently asked SQ interview questions and answers that is why, you must be prepared for such topics.
Q74). What is Consistency?
Consistency demonstrates that information won't be reflected by different clients until the information is submitted, with the goal that consistency is maintained.
Q75). What is an autonomous transaction?
An autonomous transaction is an independent exchange of the primary or parent exchange. It isn't settled in the event that it is begun by another exchange.
Q76). Where are the Pre_defined_functions located?
This is how you should answer these kinds of SQL interview questions.
They are located and stored in the standard package called "Functions, Procedures, and Packages"
Q77). Can you execute 2 queries simultaneously in a Distributed Database System?
Yes, they can be executed simultaneously as the queries are always independent of each other
Q78). What is the function that is used to transfer a PL/SQL table log to a database table?
In order to transmit a PL/SQL table log a database log table function called "PROCEDURE ps2db" is utilized. When preparing for your interview, do never miss such basic SQL questions for interview.
Q79). Elucidate the use of function "module procedure" in PL/SQL?
The "module procedure" allows changing all the lines of code in a certain program unit with a single procedure call.
Q80). What is Oracle?
Oracle is one of the prevalent databases given by Oracle Corporation, which deals with social administration ideas and subsequently it alludes as Oracle RDBMS also.
Q81). Difference between varchar and varchar2 data types?
Varchar can store up to 2000 bytes and varchar2 can store up to 4000 bytes. Varchar will consume space for NULL qualities and Varchar2 won't consume any space. Both are varied with respect to space. When you are looking to prepare for a SQL interview, make sure not to miss these kinds of SQL test interview questions.
Q82). In which language Oracle has been developed?
Oracle has been primarily developed using the language C.
Q83). What is RAW datatype?
The RAW datatype is utilized to store values in the paired information group. The most extreme size for raw in a table in 32767 bytes.
Q84). What is the use of NVL function?
The NVL work is utilized to supplant NULL values with another or given value. Example is – NVL(Value, replace value)
Q85). What are nested tables?
This is how you can answer these kinds of SQL interview questions and be prepared for your career.
A nested table is a data type in Oracle which is utilized to help sections containing multi esteemed properties. It additionally holds the whole subtable.
Q86). What is DML?
Information Manipulation Language (DML) is utilized to get to and control information in the current articles. DML statements are embedded, select, update and erase and it won't certainly submit the current transaction. Candidates find these types of common SQL interview questions typical to answer, focus on practicing more.
Q87). What is the key-preserved table?
A table is set to be a key saved table if each key of the table can likewise be the key to the consequence of the join. It assurances to return just a single duplicate of each column from the base table.
Q88). What do you mean by GROUP BY Clause?
A GROUP BY condition can be utilized in the select explanation where it will gather information over numerous records and gathering the outcomes by at least one sections. This is one of frequently asked SQL interview questions and answers you cannot miss.
Q89). How can we create privileges in Oracle?
A benefit is only ideal to execute a SQL inquiry or to get to another client object. The benefit can be given as framework benefit or client benefit. [sql]GRANT user1 TO user2 WITH MANAGER OPTION;[/sql]
Q90). What is VArray?
VArray is Oracle information typically used to have sections containing multivalued qualities and it can hold a limited cluster of qualities.
Q91). How do we get field details of a table?
Describe is utilized to get the required field details of a specified table. When preparing for your interview, do never miss such basic SQL questions for interview.
Q92). What are the SET operators?
SET operators are utilized with at least two inquiries and those administrators are Union, Union All, Intersect and Minus.
Q93). How can we delete duplicate rows in a table?
Duplicate rows in the table in SQL server can be erased by utilizing ROWID
Q94). What is an integrity constraint?
An integrity constraint is a presentation characterized a business rule for a table segment. Respectability requirements are utilized to guarantee exactness and consistency of information in a database. This is one of frequently asked SQ interview questions and answers you must include in your preparation list.
Q95). What is an ALERT?
An alert is a window which shows up in the focal point of the screen overlaying a segment of the present showcase.
Q96). What is a hash cluster?
Hash Cluster is a procedure used to store the table for quicker recovery. Apply hash an incentive on the table to recover the rows from the table.
Q97). What is the parameter mode that can be passed to a procedure?
Parameter mode is an important topic in SQL, you must prepare for the related SQL interview questions.
IN, OUT and INOUT are the methods of parameters that can be passed to a strategy.
Q98). What are the privileges?
Privileges are the rights to execute SQL proclamations – implies Right to interface and associate.
Q99). What is the data type of DUAL table?
The DUAL table is a one-section table present in prophet database. The table has a solitary VARCHAR2(1) segment called DUMMY which has a value of 'X'.
Include these major SQL topics in your preparation list to be prepared for all type of SQL questions interview.
Q100). What is the quickest way to fetch the data from a table?
The snappiest method to bring the information is to use ROWID in the SQL Query.
Q101). How does normalization work?
The process of efficiently structuring data in a database is known as normalization. It involves building tables, establishing connections between them, and specifying the rules for those connections. These rules can be used to control consistency and redundancy, giving the database more flexibility.
Q102). Identify the differences between checkpoint and commit.
The commit action ends the current transaction in the section and makes sure that the data consistency of the transaction is upheld. Commit creates a brand-new entry in the log that details the memory COMMIT. In contrast, a checkpoint is used to write all modifications that were made and kept in control and data file header files up to SCN and were committed to disc.
Q103). What does SQL's pattern matching mean?
This is how you can answer these kinds of SQL interview questions and land your dream job in the SQL.
If you are unsure of what that word should be, SQL pattern matching allows you to search for patterns in data. Instead of entering the exact word, this kind of SQL query employs wildcards to match a string pattern. To retrieve the necessary data, the LIKE operator is utilized in conjunction with SQL Wildcards.
Q104). OLTP: What is it?
Online Transaction Processing, or OLTP, is a group of software tools that may handle programs that are transaction-oriented. An OLTP system's capacity to maintain concurrency is a crucial feature. OLTP systems are frequently dispersed to prevent single points of failure.
Q105). Denormalization: What is it?
Denormalization is the inverse process of normalization, where the normalized schema is converted into a schema that has redundant information.
Q106). What do tokens in PostgreSQL mean?
A token in PostgreSQL is any symbol with a unique personality, including a keyword, identifier, literal, constant, and quotes identifiers. The use of a space, newline, or tab may or may not be used to separate them. The tokens are typically commands with relevant meanings if they are keywords. Building blocks of any PostgreSQL code are known as tokens. When preparing for your interview, do never miss such basic SQL questions for the interview.
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Q107). What is the PostgreSQL table capacity?
This is how you should answer these kinds of SQL interview questions.
PostgreSQL can be as large as 32TB.
Q108). What do PostgreSQL parallel queries entail?
PostgreSQL offers the ability to enable parallel queries, allowing developers to create query plans that can take advantage of several CPU processors to speed up query execution.
Q109). Explain the differences between checkpoint and commit.
The commit action ends the current transaction in the section and makes sure that the data consistency of the transaction is upheld. Commit creates a fresh entry in the log for the CO.
Q110). What is a restriction?
The correct format is given below on how you can answer these kinds of SQL interview questions.
The constraint is used to define the guidelines and rules that permit or impose restrictions on the values and data that can be stored in the table. It guarantees the integrity and accuracy of the data inside the tableMMIT to the memory.
Q111). What do the SQL set operators do?
To combine data from one or more tables of the same type, we utilize the set operators. The set operators and SQL joins are similar, but there are several key differences. SQL set operators aggregate records from various queries, whereas SQL joins combine columns from various tables. Yes. Instead of using the WHERE clause to sort a column, we can utilise the alias technique in the ORDER BY clause.
Q112). What does SQL's INNER JOIN mean?
This is how you should dea with these kinds of SQL interview questions and answer correctly. Inner join conceals additional rows and columns and only delivers data from the tables that matches the given condition. In plain English, it collects rows whenever there is at least one row match between the tables. The keyword INNER JOIN joins the identical records from two tables. It is optional to use the INNER keyword in the query because it is anticipated that a default join will be used.
Q113). What does SQL's Left Join mean?
All rows from the left-hand table and shared records between the specified tables are fetched using the left join. Even when there are no matches on the right-side table, it nevertheless returns all the rows from the left-side table.
Q114). What is Normalization's main application?
The major purposes of normalization are to add, remove, or change a field that can be made in a single table. Normalization is mostly used to get rid of redundant information and update, eliminate, and insert distractions. To reduce the likelihood of redundancy, normalization divides the table into manageable divisions and then connects them using various relationships. This is one of frequently asked SQ interview questions and answers.
Q115). What is a reliance that is inconsistent?
A missing or broken path to the data causes it to be difficult to obtain pertinent information, which is referred to as an inconsistent dependency. It causes users to look up information in the wrong table, which produces an error.A database object with no values is called a view. It is
Q116). What does a SQL view mean?
A database object with no values is called a view. It is a virtual table that only holds a portion of a table's data. It appears to be a real table with rows and columns, but since it is not physically there, it takes up less room. Although it doesn't have any data of its own, it functions in a manner similar to the base table. It always has a special name. This is how you should answer such important SQL interview questions.
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Q117). What does database denormalization mean?
Database managers employ the denormalization technique to boost the effectiveness of their database system. The notion of denormalization is founded on normalization, which is described as correctly organizing a database into tables for a specific purpose. Go through such SQL topics once to ensure you have good command of these basic SQL questions in the interview.
Q118). What does SQL's clustered index mean?
The data for the rows are kept in a table called a clustered index. The key values, which can only sort in one direction, are used to decide the order in which the table's data will be displayed. There can only be one clustered index per table. When the primary key is generated, it is the sole index that is automatically created.
Q119). What does SQL's non-clustered index do?
Non-clustered indexes are any indexes that are not PRIMARY indexes (clustered indexes). We are aware that when primary keys are formed, clustered indexes are automatically created, and that when numerous join conditions and different filters are used in the query, non-clustered indexes are created.
Q120). What is OLTP?
Check out the format given below to answer these kinds of SQL interview questions.
Online transaction processing, or OLTP, enables enormous teams of individuals to carry out a sizable number of database operations in real-time, typically over the internet. When data is modified, added, removed, or queried in a database, a database transaction takes place.
Q121). Describe SQL Injection.
The ability to access, retrieve, and remove sensitive data from databases is made possible by a bug in website and web app code known as SQL injection.
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Q122). What are the comments in SQL?
SQL Comments are used to add clarification to certain areas of SQL statements as well as to stop them from being executed. In many programming languages, comments play a significant role. Unsupported by a Microsoft Access database is the comments. Make sure not to miss these kinds of top SQL interview questions.
Q123). What is the difference between DELETE and TRUNCATE statements?
The TRUNCATE command is used to delete all the rows from the table and free the space containing the table.
The DELETE command deletes only the rows from the table based on the condition given in the where clause or deletes all the rows from the table if no condition is specified. But it does not free the space containing the table. Candidates find these types of top SQL interview questions typical to answer, so you need to practice more.
Q124). What is OLTP?
OLTP stands for Online Transaction Processing, is a class of software applications capable of supporting transaction-oriented programs.
Q125). What is a Stored Procedure?
A stored procedure is a subroutine available to applications that access a relational database management system (RDBMS). Such procedures are stored in the database data dictionary.
Q126). What is Pattern Matching in SQL?
The complete answer is given below on how you should answer these kinds of SQL interview questions.
SQL pattern matching provides for pattern search in data if you have no clue as to what that word should be. This kind of SQL query uses wildcards to match a string pattern, rather than writing the exact word. The LIKE operator is used in conjunction with SQL Wildcards to fetch the required information.
Q127). How are indexes defined in PostgreSQL?
PostgreSQL has built-in functions called indexes that are used by queries to search a database table.
Q128). What do tokens in PostgreSQL mean?
A token in PostgreSQL is any symbol with a unique personality, including a keyword, identifier, literal, constant, and quotes identifiers. The use of a space, newline, or tab may or may not be used to separate them.
Q129). What does "multi-version concurrency control" mean to you?
This is how you should answer these kinds of SQL interview questions.
When multiple requests are trying to access or edit the same data at once, MVCC, or multi-version concurrency control, is used to prevent needless database locks.
Q130). What distinguishes the "BETWEEN" and "IN" condition operators most significantly?
While the IN condition operator is used to check for values present in a certain set of values, the BETWEEN operator is used to show rows based on a range of values in a row. This is how you can answer these kinds of SQL interview questions and excel in your career.
Q131). Why is a MERGE statement necessary?
This clause permits data to be updated or added to a table under certain conditions. If a row already exists, it updates it; otherwise, it inserts a row. Candidates find these types of top SQL interview questions typical to answer, so you need to practice more.
Q132). What do you mean by a stored procedure that recurs?
A stored procedure is referred to as recursive if it keeps calling itself until it encounters a boundary condition. The programmers can reuse the same body of code by using this recursive function or process.
Q133). What does SQL's auto increment mean?
This is how you should answer these kinds of SQL interview questions.
When a new record is inserted into the table, the autoincrement keyword enables the user to construct a unique number that will be created.
Q134). What does SQL's WITH clause mean?
Only the query in which the WITH clause appears has access to the definition of a temporary relationship defined by the WITH clause. Aggregate functions can be utilized because SQL applies predicates in the WITH clause after groups have been created.
Q135). Why do you use the word "collation"?
A set of guidelines that specify how data can be sorted and compared is known as collation. With options to determine case sensitivity, character width, etc., character data is sorted using the rules that provide the proper character sequence.
Q136). What function does MySQL's tee command serve?
Tee is a UNIX command that sends a command's standard output to the terminal as well as a file. The character tee followed by a filename enables MySQL logging to that particular file. A command note has the ability to pause it.
Q137). Federated tables: what are they?
This is one of the SQL basic interview questions you can't miss. Federated tables in MySQL give users access to the tables located on other databases on different servers. It enables you to use a distant MySQL database without needing replication or cluster technology to access the data there.
Q138). How can videos be stored in a SQL Server table?
This is how you should answer these kinds of SQL interview questions and crack your dream job at the first attempt.
To store videos in a SQL server table, we use the FILESTREAM datatype.
Q139). What is a database cursor?
The technology that enables traversal over a database's records is called a database cursor. Cursors also enable processing following traversal, such as database record retrieval, insertion, and deletion. A cursor behaves similarly to an iterator in a computer language.
Q135). Explain SQL comments.
This is how you can answer these kinds of SQL interview questions. The sections of the SQL statements are clarified using SQL comments. Additionally, they assist in preventing the execution of SQL commands.
Q136). Describe a deadlock.
When two or more transactions are waiting impatiently for one another to unlock the locks, it is an undesirable circumstance. Candidates find these types of top SQL interview questions typical to answer, so you need to practice more.
Q137). Describe the left outer join with an example.
If you want all the data from the left table (first table) and only the data that matches from the second table, you can use a left outer join. Records that are not matched are null records. Example: Left outer join with the plus sign "+" Choose rows from tables 1 and 2 where t1.col=t2.col(+) and t1.col=t2.coln; Candidates find these types of top SQL interview questions typical to answer, so you need to practice more.
Q138). SQL injection definition.
A code injection method called SQL injection is used to break into data-driven systems. This is one of the SQL basic interview questions you can't miss.
Q139). A UNION operator is what?
By eliminating duplicate rows, the UNION operator combines the results of two or more Select statements. The columns and data types in the SELECT must match.
Q141). Describe the SQL constraints.
A table's data type rules are specified using SQL Constraints. They can be specified both during table creation and table modification. The SQL constraints are as follows: BARELY NULL CHECK DELIVERED UNIQUE FOREIGN KEY FOR PRIMARY KEY
Q142). What does ALIAS command mean?
This command gives a table or column a different name. It can be utilised in a SQL query's WHERE clause by utilising the "as" keyword.
Q143). How do group functions work? What makes us require them?
One result per group is produced by group functions when applied to a set of rows. These group functions are frequently used: AVG, MAX, MIN, SUM, VARIANCE, and COUNT.
Q144). Describe CLAUSE.
By supplying criteria to the query, a SQL clause is built to limit the result set. This typically selects a few rows from the entire collection of records. A query with a WHERE condition is an example.
Q145). What is a recursive stored procedure?
This is how you should answer these kinds of SQL interview questions.
Up until it encounters a boundary condition, a stored procedure calls by itself. Programmers can reuse the same code multiple times thanks to this recursive function or process.
Q146). What accomplishes the BCP command?
This is how you should answer these kinds of SQL interview questions and make yourself stand out. Data can be exported or imported from a table into a file and vice versa using the Bulk Copy utility or tool.
Q147). How do you cross join?
Every row from the two tables is combined in the result set of a SQL cross join. Additionally known as cross product set.
Q148). Which operator does pattern matching in a query?
This is how you should answer these kinds of SQL interview questions.
When matching patterns, the LIKE operator is employed, and it can be utilised as 0.1% - Matches 0 or more characters. 2. _(Underscore) - Exact character match.
Q149). To get the current date, can you write a SQL query?
SELECT CURRENT DATE();
Q150). What does lock escalation mean?
The smallest row level lock that may be obtained by a query is first used. Locks are escalated to range or page locks when there are too many locked rows. A table lock may occur if there are too many locked pages. This is one of the SQL basic interview questions you can't miss.
Q151). How can videos be stored in a SQL Server table?
Utilizing the SQL Server 2008-introduced FILESTREAM datatype.
Q152). What is the SQL SELECT order?
Here is the format how you can answer these kinds of SQL interview questions. The SQL SELECT clauses are in the following order: SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY The only necessary clauses are SELECT and FROM.
Once you have read all these questions before going for your interview, I am sure that you will feel inert and confident in yourself. Think of joining a professional SQL Training Program to prepare for your interview well in a renowned institute like JanBask Training. Also, take note that in case you do not know an answer, do not lose hope or start thinking negatively outright. It is neither possible nor expected from you to know everything under the sun about the topic.
Best of Luck!
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