# How to Use SQL IF Statement

SQL is a programming language used for managing and manipulating data in a relational database. One of the most important aspects of SQL is its conditional statements, which allow you to execute different SQL statements based on certain conditions. In this tutorial, you will learn how to use the SQL IF statement to execute different SQL queries based on a condition.

## Understanding the IF Statement

The IF statement in SQL is used to execute a set of SQL statements based on a specific condition. The syntax for the IF statement is as follows:

``````IF (condition)
BEGIN
-- SQL statements
END
``````

The condition is a logical expression that returns either True or False. If the condition is True, the SQL statements within the BEGIN and END block will be executed.

## Examples

Let’s take a look at some examples of how to use the IF statement in SQL.

### Example 1: Basic IF Statement

Suppose we have a table called “employees” with two columns: “name” and “salary”. We want to select all employees with a salary greater than 50000. Here is how we can do it using the IF statement:

``````IF (SELECT salary FROM employees WHERE salary > 50000) IS NOT NULL
BEGIN
SELECT name, salary FROM employees WHERE salary > 50000
END
``````

In this example, the IF statement checks whether there is at least one employee with a salary greater than 50000. If the condition is True, the SQL statement within the BEGIN and END block will be executed, which will select all employees with a salary greater than 50000.

### Example 2: IF-ELSE Statement

Suppose we have the same “employees” table, but this time we want to select all employees with a salary greater than 50000 and all employees with a salary less than or equal to 50000. Here is how we can do it using the IF-ELSE statement:

``````IF (SELECT salary FROM employees WHERE salary > 50000) IS NOT NULL
BEGIN
SELECT name, salary FROM employees WHERE salary > 50000
END
ELSE
BEGIN
SELECT name, salary FROM employees WHERE salary <= 50000
END
``````

In this example, the IF statement checks whether there is at least one employee with a salary greater than 50000. If the condition is True, the first SQL statement within the BEGIN and END block will be executed, which will select all employees with a salary greater than 50000. If the condition is False, the SQL statement within the ELSE block will be executed, which will select all employees with a salary less than or equal to 50000.

### Example 3: IF-ELSEIF-ELSE Statement

Suppose we have a table called “students” with three columns: “name”, “grade”, and “age”. We want to select all students with a grade of “A”, all students with a grade of “B”, and all students with a grade other than “A” or “B”. Here is how we can do it using the IF-ELSEIF-ELSE statement:

``````IF (SELECT name FROM students WHERE grade = 'A') IS NOT NULL
BEGIN
END
ELSE IF (SELECT name FROM students WHERE grade = 'B') IS NOT NULL
BEGIN
END
ELSE
BEGIN
SELECT name, grade, age FROM students WHERE grade NOT IN ('A', 'B')
END
``````

In this example, the IF statement checks whether there is at least one student with a grade of “A”. If the condition is True, the first SQL statement within the BEGIN and END block will be executed, which will select all students with a grade of “A”. If the condition is False, the ELSE IF statement checks whether there is at least one student with a grade of “B”. If the condition is True, the second SQL statement within the BEGIN and END block will be executed, which will select all students with a grade of “B”. If both conditions are False, the ELSE statement will be executed, which will select all students with a grade other than “A” or “B”.

## Troubleshooting Tips

• Make sure the condition is a logical expression that returns either True or False
• Make sure the SQL statements within the BEGIN and END block are valid SQL statements
• Make sure to use the correct syntax for the IF statement
• Use the IS NOT NULL operator to check whether a subquery returns any rows

## Conclusion

The IF statement in SQL is a powerful tool that allows you to execute different SQL statements based on a condition. By using the IF-ELSEIF-ELSE statement, you can execute multiple SQL statements based on multiple conditions. With these conditional statements, you can manage and manipulate your data in a more efficient and effective way.