Usage of if else in sql

IF ELSE statement allows performing different actions based on conditions in a SQL query. It is used for conditional checking and executes the statement specified in THEN or ELSE based on the result. The syntax is: IF condition THEN operation 1 ELSE operation 2 END IF. Example: SELECT Product, IF(Product = 'Book', 'Book', 'Magazine') AS ProductType FROM Sales; Displays a "Book" or "Magazine" message based on the value of the Product column.

Usage of IF ELSE statement in SQL

The IF ELSE statement allows you to perform conditional checks in SQL queries. and perform different actions based on the results.

Syntax:

<code>IF 条件 THEN
    操作1
ELSE
    操作2
END IF;</code>

Example:

Suppose you have a table named "Sales" that contains each "Product" and "Amount" columns for each order. To check whether the product type in each order is "Book" or "Magazine" and display a different message accordingly, you can use the following IF ELSE statement:

<code>SELECT
    Product,
    IF(Product = 'Book', '这是订购的书籍', '这是订购的杂志') AS ProductType
FROM Sales;</code>

Explanation:

• Conditional checks are specified in parentheses: Product = 'Book'.
• If the condition is true (the product is "Book"), perform the THEN operation: display "This is the ordered book".
• If the condition is false (the product is not "Book"), perform the ELSE action: display "This is the magazine ordered".

Note:

• IF ELSE statements can be nested to handle more complex conditions.
• The ELSE clause is optional, if you do not specify an ELSE clause, no action will be performed when the condition is false.
• The result of the condition check must be a Boolean value (true or false).
• The operation in the IF ELSE statement can be any valid SQL statement, including SELECT, INSERT, UPDATE, and DELETE.

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