添加对值的约束，Mysql

Question

我的table

CREATE TABLE STUDENT ( 
      BCN INT not null,
      Stname varchar(50) not null,
      Sex char(1) not null ,
      primary key (BCN));

我想让 Sex 属性只接受两个值 'F' 或 'M'

我试过 'check' 子句：

 Sex char(1) not null check (Sex = 'F' or Sex ='M' )

但不起作用，“性别”列仍然接受其他值，例如 ('B') !

我已经尝试创建触发器：

DELIMITER $$ CREATE TRIGGER SexCheck BEFORE INSERT ON student
FOR EACH ROW
BEGIN
    IF Sex <> 'M' and Sex <> 'F' THEN
    SIGNAL SQLSTATE '10000'
        SET MESSAGE_TEXT = 'check constraint on Student.Sex failed';
    END IF;
END$$   
DELIMITER ;

它不会产生任何语法错误，但性别列甚至不接受任何值 'M' 或 'F'！它显示了我设置的消息。

我该如何解决？

-我正在使用 mysql workbench 6.3.

提前致谢

Answer 1

来自CREATE TABLE:

The CHECK clause is parsed but ignored by all storage engines.

第二个：

CREATE TRIGGER SexCheck BEFORE INSERT ON  STUDENT
FOR EACH ROW
BEGIN
    IF New.Sex NOT IN('F', 'M') THEN
    SIGNAL SQLSTATE '10000'
        SET MESSAGE_TEXT = 'check constraint on Student.Sex failed';
    END IF;
END;


INSERT INTO STUDENT(Sex) VALUES ('B');
-- check constraint on Student.Sex failed

SqlFiddleDemo

Answer 2

使用 MySQL ENUM 类型。 "An ENUM is a string object with a value chosen from a list of permitted values that are enumerated explicitly in the column specification at table creation time."

sex ENUM ('M', 'F')

添加对值的约束，Mysql

Add constraint on values , Mysql

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