How to make a SQL "IF-THEN-ELSE" statement

When working with databases, you often need conditional logic to control what data gets returned. A common question developers ask is: “How do I write an IF-THEN-ELSE statement in SQL?” While SQL doesn’t have a direct IF-THEN-ELSE command like traditional programming languages, it provides functions and expressions that achieve the same result.

Using CASE Statement (Most Common):

 The CASE expression is the standard way to handle conditional logic in SQL.

 SELECT 
    employee_name,
    salary,
    CASE 
        WHEN salary > 50000 THEN 'High Salary'
        ELSE 'Standard Salary'
    END AS salary_category
FROM employees;

  Here, the query checks each employee’s salary and categorizes it accordingly.

Using IF Function (MySQL specific):

 In MySQL, you can also use the IF() function directly.

 SELECT 
    employee_name,
    IF(salary > 50000, 'High Salary', 'Standard Salary') AS salary_category
FROM employees;

  This works like a shorthand IF-THEN-ELSE.

Stored Procedures with IF-ELSE:

 Inside stored procedures, you can use IF...ELSE blocks to control flow:

 IF salary > 50000 THEN
    SET category = 'High Salary';
ELSE
    SET category = 'Standard Salary';
END IF;

 Key Takeaway:

• Use CASE when writing queries (works in all SQL databases).
  
• Use IF() in MySQL for simpler conditions.
  
• Use IF...ELSE inside stored procedures for advanced logic.
  

This way, SQL lets you implement conditional checks just like an IF-THEN-ELSE structure in programming.