mysql自定义函数写法

CREATE FUNCTION function_name (parameter_list)
RETURNS data_type
[characteristic ...]
BEGIN
    -- 函数体
    DECLARE variable_name data_type;
    -- ...
    RETURN expression;
END;

DELIMITER //

CREATE FUNCTION AddNumbers(x INT, y INT)
RETURNS INT
DETERMINISTIC
BEGIN
    RETURN x + y;
END;

//

DELIMITER ;

CREATE FUNCTION function_name (parameter_list)
RETURNS TABLE (column_definition)
[characteristic ...]
BEGIN
    -- 函数体
    -- ...
END;

DELIMITER //

CREATE FUNCTION NumbersInRange(start INT, end INT)
RETURNS TABLE (number INT)
DETERMINistic
BEGIN
    DECLARE i INT DEFAULT start;
    WHILE i <= end DO
        INSERT INTO NumbersInRange(number) VALUES (i);
        SET i = i + 1;
    END WHILE;
END;

//

DELIMITER ;