DBA MySQL枚举集合

ENUM

​ 枚举类型从众多选项成员中提取出一个选项,类似于单选的概念,最大可指定65535个选项。

​ 如果插入值不在其选项成员中,将会插入空字符。

CREATE TABLE userinfo(
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT "用户编号",
    name CHAR(12) NOT NULL COMMENT "用户姓名",
    age TINYINT(3) NOT NULL DEFAULT 0 COMMENT "用户年龄",
    gender ENUM("male", "female", "unknow") DEFAULT "unknow" COMMENT "用户性别"
) ENGINE innodb CHARSET utf8mb4 COLLATE utf8mb4_general_ci;

​ 尝试对其进行插入操作,如果插入选项不在ENUM的选项成员中,则结果为空:

M > INSERT INTO
           userinfo (name, age, gender)
       VALUES
           ("Jack", 22, "other");

M > SELECT * FROM userinfo LIMIT 1;
+----+--------------+-----+--------+
| id | name         | age | gender |
+----+--------------+-----+--------+
|  1 | Jack         |  22 |        |
+----+--------------+-----+--------+

SET

​ 集合类型从众多选项成员中提取出多个选项,类似于多选的概念,最大可指定64个选项。

​ 如果插入值中有一个不在其选项成员中,将会插入空字符,在其选项成员中的值将会被正确插入。

CREATE TABLE userinfo(
    id INT PRIMARY KEY AUTO_INCREMENT COMMENT "用户编号",
    name CHAR(12) NOT NULL COMMENT "用户姓名",
    age TINYINT(3) NOT NULL DEFAULT 0 COMMENT "用户年龄",
    gender ENUM("male", "female", "unknow") DEFAULT "unknow" COMMENT "用户性别",
    hobby SET("basketball", "football", "volleyball", "unknow") DEFAULT "unknow" COMMENT "用户爱好"
) ENGINE innodb CHARSET utf8mb4 COLLATE utf8mb4_general_ci;

​ 对集合类型字段进行插入时,可按照选项1,选项2的方式进行插入。如下所示:

M > INSERT INTO
           userinfo(name, age, gender, hobby)
       VALUES
           ("Jack", 22, "male", "basketball,football");

M > SELECT * FROM userinfo LIMIT 1;
+----+--------------+-----+--------+---------------------+
| id | name         | age | gender | hobby               |
+----+--------------+-----+--------+---------------------+
|  1 | Jack         |  22 | male   | basketball,football |
+----+--------------+-----+--------+---------------------+

使用建议

​ 无论是ENUM还是SET,选项成员都应该是字符类型。

posted @ 2021-02-17 12:45  云崖君  阅读(42)  评论(0编辑  收藏  举报