MySQL 触发器，模糊的语法错误

Question

使用 MySQL 5.5，以下触发器因错误而被拒绝:

create trigger nodups
before insert on `category-category`
for each row
begin
    if(catid >= relatedid) then
        signal 'catid must be less than relatedid';
    end if
end;

我收到以下错误:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '-category for each row begin if(catid >= relatedid) then signal 'catid must be l' at line 1

这个触发器的语法有什么问题？

就其值(value)而言，我只是试图阻止使用 catid >= relatedid 进行插入。我对实现这一目标的其他方法持开放态度。

---

编辑:上面的查询在单行、分号和所有内容中输入。

我使用分隔符再次尝试。这是结果:

mysql> delimiter ###
mysql> create trigger nodups
    -> before insert on `category-category`
    -> for each row
    -> begin
    -> if(catid >= relatedid) then   
    -> signal 'catid must be less than relatedid';
    -> end if
    -> end;
    -> ###
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''catid must be less than relatedid';
end if
end' at line 6

Answer 1

- 是一个特殊字符。您需要使用反引号转义包含特殊字符的表

delimiter |
create trigger nodups
before insert on `category-category`
for each row
begin
    if(catid >= relatedid) then
        SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'catid must be less than relatedid';
    end if;
end;
|
delimiter 

您还需要更改分隔符。否则 DB 认为您的触发器定义在第一个 ; 结束，这将是不完整的。