所有表和字段都要添加注释COMMENT,从一开始就进行数据字典的维护 尽量控制单表数据量的大小在500w以内,超过500w可以使用历史数据归档,分库分表来实现(500万行并不是MySQL数据库的限制。过大对于修改表结构,备份,恢复都会有很大问题。MySQL没有对存储有限制,取决于存储设置和文件系统) 谨慎使用mysql分区表(分区表在物理...
· 错误:1342 SQLSTATE: HY000 (ER_FPARSER_EOF_IN_COMMENT) 消息:解析’%s’时,文件意外结束。 · 错误:1343 SQLSTATE: HY000 (ER_FPARSER_ERROR_IN_PARAMETER) 消息:解析参数’%s’时出错(行:’%s’)。 · 错误:1344 SQLSTATE: HY000 (ER_FPARSER_EOF_IN_UNKNOWN_PARAMETER) 消息:跳过未知参数’%s’...
可以看到,建立唯一性索引时使用的是“ADD KEY”而不是“ADD INDEX”。如果你使用的是“ADD INDEX”,即使你在语句中使用了 UNIQUE 关键字,MySQL也会将它视为“ADD KEY”。 因此,在MySQL中,“ADD KEY”和“ADD INDEX”的主要区别在于前者用于创建唯一性索引,而后者用于创建普通索引。但是在实际使用中,建议我们使用...
我想要往 job 表中 insert 一条数据,报错如题。 原因:要插入 job 表的数据中外键列的值有问题,userId 字段的值在 user 表中找不到。 解决: 确保 job 表中要引用的外键值在 user 表中有对应数据就可以了。 “ you're adding a foreign key, you need to make sure that the data in the child tabl...
Now that MySQL 5.7 supports utf8mb4 better, the main restriction is actually that you need to set the server encoding and JDBC URL such that the connection uses the right encoding. This is documented in workaround 2 below. Workaround 1 You can switch to another of the databases supported ...
这是mysql本身的规定,和 语言特征, 只能对数据库中的表和字段进行comment, 不能对数据库本身进行注释 mysql中的enum枚举类型和set集合类型,是复合类型的变量, 是mysql对标准sql的扩展. 他们 都是以字符串的形式出现的 , 只是 在数据库内部存储时, 是作为整数类型来处理的。 本身的列举值是字符串型。
mysql> ALTER TABLE t2 DROP COLUMN d, ALGORITHM = INSTANT; Query OK, 0 rows affected (0.40 sec) Records: 0 Duplicates: 0 Warnings: 0 mysql> # Do two operations instantly in the same statement mysql> ALTER TABLE t2 ALTER COLUMN a SET DEFAULT 20, ALTER COLUMN b SET DEFAULT 200, ALGORITH...
in se_private_data of the mysql.tables 5. For "old" rows, the default value will be looked up from the new system tables and appended before return to server. 6. For the duraton of instant adding column, MDL will be placed and maintained on the table. In this way, we can instantly...
Options:Reply•Quote Subject Views Written By Posted ADD column in Partitioned table 2305 kaveen v November 08, 2017 12:49AM Re: ADD column in Partitioned table 1191 Peter Brawley November 08, 2017 10:52AM Sorry, you can't reply to this topic. It has been closed. ...
Cant add "." in a table namePosted by: GhOsT TeCh Date: July 31, 2008 10:44PM Hey im trying to reanme my current table "tt" to "ghost.tech" how ever when i enter the command in the sql section of phpMYadmin it says sucsefful then when i look at the database , the ...