插入时mysql触发器,如果​​行不存在

Question

我的触发器不起作用.

基本上,当user_briefcase创建a时,user_complementary_info 如果它还不存在,我还想创建一个行,其中user_complementay.user_id=新创建的行user_briefcase.user_id

我的触发器

DROP TRIGGER IF EXISTS complementary_user_info
DELIMITER $$
CREATE TRIGGER complementary_user_info AFTER INSERT user_briefcases FOR EACH ROW
BEGIN
IF (SELECT COUNT(*) user_complementary WHERE user_id=NEW.user_briefcases.user_id) = 0 THEN
    INSERT INTO user_complementary (user_id)
    VALUES (NEW.user_briefcases.user_id)

END $$
DELIMITER ;

Answer 1

DROP TRIGGER IF EXISTS complementary_user_info;
DELIMITER $$
CREATE TRIGGER complementary_user_info AFTER INSERT user_briefcases FOR EACH ROW
BEGIN
IF NOT EXISTS (SELECT 1 FROM user_complementary_info WHERE user_id = NEW.user_id) THEN
    INSERT INTO user_complementary (user_id)
    VALUES (NEW.user_briefcases.user_id);
END IF;
END $$
DELIMITER ;