无法创建mysql触发器

Question

我尝试在 phpmyadmin 上限制 MySQL 中的重叠时间段，因此新记录不能包含相同的 pc_id 和日期，因为您不能多次提供同一台计算机。请帮助我。

CREATE TRIGGER history_insert_overlap
    BEFORE INSERT ON history
    FOR EACH ROW
BEGIN
IF EXISTS (SELECT COUNT(*) FROM history WHERE `NEW.pc_id` =`pc_id` AND `NEW.date` BETWEEN `date` AND `date_return`) THEN
BEGIN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Interval Overlaps Existing Intervals';
END;
END IF;
END;

我收到错误 1064。

Answer 1

对于错误 1064 - sql 查询语法：将

NEW.pc_id

更改为 NEW。

pc_id

看例子

CREATE TRIGGER history_insert_overlap
    BEFORE INSERT ON history
    FOR EACH ROW
BEGIN
IF EXISTS (SELECT 1 FROM history 
          WHERE NEW.`pc_id` =`pc_id` 
            AND NEW.`date` BETWEEN `date` AND `date_return`) THEN
BEGIN
SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Interval Overlaps Existing Intervals';
END;
END IF;
END;