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[数据库]MySQL: LEAVE Statement


https://www.techonthenet.com/mysql/loops/leave.php

 

This MySQL tutorial explains how to use the LEAVE statement in MySQL with syntax and examples.


Description

In MySQL, the LEAVE statement is used when you want to exit a block of code identified by a label_name, such as a LOOP statement, WHILE statement, or REPEAT statement.


Syntax

The syntax for the LEAVE statement in MySQL is:

LEAVE label_name;

Parameters or Arguments

label_name
The name of the block of code (ie: LOOP, WHILE, REPEAT) to terminate.

Note

  • You use the LEAVE statement to terminate a block of code, such as a LOOP statement, WHILE statement, or REPEAT statement that is identified by a label_name.

Example

Let's look at an example that shows how to use the LEAVE statement in MySQL:

DELIMITER //CREATE FUNCTION CalcIncome ( starting_value INT )RETURNS INTBEGIN  DECLARE income INT;  SET income = 0;  label1: LOOP   SET income = income + starting_value;   IF income < 3000 THEN    ITERATE label1;   END IF;   LEAVE label1;  END LOOP label1;  RETURN income;END; //DELIMITER ;

In this LEAVE example, we have created a loop called label1 using the LOOP statement.

The ITERATE statement would cause the loop to repeat while income is less than 3000. Once income is greater than or equal to 3000, the LEAVE statement would terminate the LOOP.