UNIQUE_Test_id int not null, #unique就是唯一约束,使用列级约束建立唯一约束 UNIQUE_Test_name varchar(45) unique ); 1. 2. 3. 4. 5. 6. 7. 如果需要为多列组合建立唯一约束,或者想自行指定约束名,则需要使用表级约束语法。 create table UNIQUE_Test ( #寄哪里非空约束,这意味着UNIQUE_Test_id不...
alter table t_s_r add unique key(t_id,s_id); # 创建表时指定 多字段联合唯一 create table t_s_r2(t_id int,s_id int,unique key(t_id,s_id)); 方式2: # 推荐 将中间的关系表 两个id 作为联合主键 同时具备了 唯一且非空约束 create table t_s_r3(t_id int,s_id int,primary key(...
Re: Composite Unique Key with NULLable DateTime Field Problem Frank Osterberg January 13, 2006 09:19AM Sorry, you can't reply to this topic. It has been closed. This forum is currently read only. You can not log in or make any changes. This is a temporary situation. ...
ALTER TABLE [dbName.]tableName MODIFY id BIGINT(20) UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT; -- 修改列(数据类型、nullable、primary key、increment) ALTER TABLE table_name MODIFY columnA CHAR(10) -- 修改 表列类型 ALTER TABLE table-name ADD PRIMARY KEY ( table-id ); -- 添加 主键...
A patch for this bug has been committed. After review, it may be pushed to the relevant source trees for release in the next version. You can access the patch from:http://lists.mysql.com/commits/1101793412 Luis Soares 2010-06-04BUG#53893: RBR: nullable unique key can lead to out-of...
当MySQL中的InnoDB表没有显式定义主键时,数据库会将所有键列都定义为not NULL的UNIQUE key视为隐式主键。启用GIPK后,即使对于使用隐式主键创建的表,也会生成主键。 以下是一个示例: -- Enable GIPK mode SET GLOBAL sql_generate_invisible_primary_key = ON; ...
NON_UNIQUE: 0 INDEX_SCHEMA: test INDEX_NAME: PRIMARY SEQ_IN_INDEX: 1 COLUMN_NAME: id COLLATION: A CARDINALITY: 0 SUB_PART: NULL PACKED: NULL NULLABLE: INDEX_TYPE: BTREE COMMENT: INDEX_COMMENT: *** 2. row *** TABLE_CATALOG: def TABLE_SCHEMA: test TABLE_NAME: test_data2 NON_UNIQUE...
UNIQUEKEY(`id`) COMMENT"OLAP" DISTRIBUTEDBYHASH(`id`)BUCKETS8; -- enable batch delete ALTERTABLEtarget_testENABLEFEATURE"BATCH_DELETE"; 注意 Doris 表结构和 Mysql 表结构字段顺序必须保持一致。 创建同步作业 CREATE SYNC `demo`.`job`
MySQL中的主键(Primary Key)是表中的一个或多个字段,用于唯一标识表中的每一行数据。主键具有以下特性: 唯一性:主键的值在整个表中必须是唯一的。 非空性:主键的值不能为空。 唯一索引:主键字段上会自动创建唯一索引,以提高查询效率。 主键冲突的原因 ...
u2 int null, unique key u1u2 (u1,u2) ); insert into utest values (null,1),(1,null),(null,null); insert into utest values (null,1),(1,null),(null,null); Columns referenced in unique keys should not be nullable. Sorry, you can't reply to this topic. It has been closed....