MYSQL检查输入值或传入null。在一个过程中

DELIMITER //

CREATE PROCEDURE InsertUser(
    IN p_username VARCHAR(50),
    IN p_email VARCHAR(100)
)
BEGIN
    DECLARE CONTINUE HANDLER FOR SQLEXCEPTION
    BEGIN
        ROLLBACK;
        RESIGNAL;
    END;

    START TRANSACTION;

    IF p_username IS NULL OR p_email IS NULL THEN
        SIGNAL SQLSTATE '45000'
        SET MESSAGE_TEXT = 'Username and email cannot be null';
    ELSEIF LENGTH(p_username) < 3 THEN
        SIGNAL SQLSTATE '45000'
        SET MESSAGE_TEXT = 'Username must be at least 3 characters long';
    ELSEIF NOT p_email LIKE '%_@__%.__%' THEN
        SIGNAL SQLSTATE '45000'
        SET MESSAGE_TEXT = 'Invalid email format';
    ELSE
        INSERT INTO users (username, email) VALUES (p_username, p_email);
    END IF;

    COMMIT;
END //

DELIMITER ;