Java All parts of a PRIMARY KEY must be NOT NULL；if you need NULL in a key,use UNIQUE instead问题解决

问题描述：Cause: java.sql.SQLSyntaxErrorException: All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead问题分析：1、设为主键的字段设置了可以为null。CREATE TABLE users(`username` varchar(2

旭东怪

7884人浏览 · 2021-09-23 21:07:58

旭东怪 · 2021-09-23 21:07:58 发布

问题描述：

Cause: java.sql.SQLSyntaxErrorException: All parts of a PRIMARY KEY must be NOT NULL; if you need NULL in a key, use UNIQUE instead

问题分析：

1、设为主键的字段设置了可以为null。

        CREATE TABLE users(
            `username` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户名',
            `password` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL COMMENT '密码',
            PRIMARY KEY (`user_name`, `password`) USING BTREE
                USING BTREE
        ) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = DYNAMIC;

解决办法：设为主键的字段设置为not null即可。

        CREATE TABLE users(
            `username` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '用户名',
            `password` varchar(20) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '密码',
            PRIMARY KEY (`user_name`, `password`) USING BTREE
                USING BTREE
        ) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = DYNAMIC;