我们可以使用ALTER TABLE语句来在现有的MySQL表的列上应用NOT NULL约束。 阅读更多:MySQL 教程 语法 ALTER TABLE table_name MODIFY colum_name datatype NOT NULL; Mysql Copy 示例 mysql>创建表test123(ID INT,DateDATE);查询已经成功,影响0行(用时0.19秒)mysql>描述test123;+---+---+-...
(0.00 sec) mysql> insert into t13 (name,age,gender) values (NULL,'18','男'); ERROR 1048 (23000): Column 'name' cannot be null mysql> insert into t13 (age,gender) values ('18','男');//如果我们没有明确指定一列要插入,用的是default,如果建表中对应列默认没有设置default值,将无法...
用alter table change语法来修改列的默认字符集,结果报错ERROR 1064. 自己没发现语法错在什么地方。 mysql> alter table goods change goods_name goods_name varchar(120) not null character set utf8 ; ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to yo...
基本语法: INSERT INTO table_name [(column1, column2, ...)] VALUES (value1, value2, ...)[, (value1, value2, ...), ...]; 插入单条数据 INSERT INTO students (name, age, gender, class, score) VALUES ('张三', 20, '男', '计算机科学1班', 89.5); 插入多条数据 INSERT INTO stu...
Hello, is it possible to create a column which must not be null and with at least one character in mySQL 5.1 and if it's practicable how to code it? (NOT NULL allows empty strings like ''!) Thanks a lot for answers!Navigate: Previous Message• Next Message Options: Reply• ...
(columnType.toString())) { alterTable += " NULL"; } } if (statement.isPrimaryKey()) { alterTable += " PRIMARY KEY"; if (database instanceof OracleDatabase) { alterTable += !statement.shouldValidatePrimaryKey() ? " ENABLE NOVALIDATE " : ""; } } if ((database in...
源代码:编译安装 需cmake https://blog.51cto.com/xiexiaojun/1679995 二进制格式的程序包:展开至特定路径,并经过简单配置后即可使用 https://blog.51cto.com/sonlich/1970069 https://blog.51cto.com/xiexiaojun/1660813 三、MariaDB,开源RDBMS的实现
ALTER TABLE 表名 MODIFY COLUMN 列名 新数据类型 [约束条件]; 1. 特点 只能修改列的数据类型和约束,不能改变列名 语法更简洁 必须保持列名不变 示例 -- 将name列的数据类型从VARCHAR(50)改为VARCHAR(100) ALTER TABLE users MODIFY COLUMN name VARCHAR(100) NOT NULL; ...
Thus I have set both null as I want to set either day or date. If the date is specified, then I can get the day from it, so it doesn't make sense to ask or force the user to set day, which may cause human error. I may use TRIGGER but would like to know if there is any...
ERROR 1846 (0A000):ALGORITHM=INPLACE is not supported. Reason: Cannot change column type INPLACE. Try ALGORITHM=COPY. 可能原因 使用INPLACE方式扩展VARCHAR字段长度时,不支持将小于256字节的字段扩展为等于或大于256字节的字段。 支持扩展的字段长度范围为: 扩展前 扩展后 小于256字节 小于256字节 等于或大于...