Usage of if else statement in sql-SQL-php.cn

IF-ELSE statement is used in SQL to perform different operations based on conditions. The basic syntax is: If the condition is true, execute statement 1. If the condition is false, statement 2 is executed. The condition is a Boolean expression and the statement can be any valid SQL statement.

Usage of if else statement in sql

Usage of IF-ELSE statement in SQL

IF-ELSE statement is used in SQL to meet certain requirements. Perform different actions when conditions occur. Its basic syntax is as follows:

IF condition THEN statement1 ELSE statement2

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Usage instructions:

##Condition (condition): Boolean expression to be evaluated.
Statement 1 (statement1): If the condition is true, the statement to be executed.
Statement 2 (statement2): If the condition is false, the statement to be executed.

Example:

SELECT CASE WHEN age >= 18 THEN '成人' ELSE '未成年' END AS age_group FROM students;

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In this example, the CASE expression uses an IF-ELSE statement to classify a student as "Adult" based on the value of the age column or "minor".

Nested IF-ELSE statements:

IF-ELSE statements can be nested to handle more complex situations. Nested IF-ELSE statements will check subsequent conditions in sequence if the first condition is not met.

IF condition1 THEN statement1 ELSE IF condition2 THEN statement2 ELSE statement3

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Tip:

Each ELSE IF statement must contain an ELSE clause.
You can also use CASE expressions as an alternative to IF-ELSE statements.

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