MySQL 循环分支语法

label: LOOP
    statement_list

    IF exit_condition THEN
        LEAVE label; 
    END IF; 
END LOOP label;

REPEAT
    statement_list
UNTIL search_condition END REPEAT;

WHILE search_condition DO
    statement_list
END WHILE;

IF search_condition THEN
    statement_list
ELSE
    statement_list
END IF;

IF search_condition THEN
    statement_list
ELSEIF search_condition THEN
    statement_list
ELSE
    statement_list
END IF;

CASE case_value
    WHEN when_value THEN
        statement_list
    ELSE
        statement_list
END CASE;

create PROCEDURE procedure_name([IN|OUT|INOUT] param_name param_type,...)
BEGIN
    statement_list
END

DROP PROCEDURE procedure_name

SELECT
    * 
FROM
    mysql.proc 
WHERE
    type = ‘PROCEDURE‘

CREATE FUNCTION function_name(param_name param_type,...)
RETURNS return_type
BEGIN
    statement_list
END

DROP FUNCTION IF EXISTS function_name

SELECT
    * 
FROM
    mysql.proc 
WHERE
    type = ‘FUNCTION‘

-- 函数(FUNCTION)或存储过程(PROCEDURE)定义变量及赋值
    -- 定义
    DECLARE variable_name variable_type DEFAULT default_value;
    -- 赋值
    SET variable_name = new_value;
    -- 在SELECT查询里进行赋值
    SELECT variable_name := col_name;