create temporary table 表名 mysql自增长 auto_increment 添加外键约束 alter table 表名 add constraint fk_引用id foreign key(引用id) references 被引用表名 (被引用id) 添加主键约束 alter table 表名 add constraint pk_id primary key (id);
INOUT: 表示输入输出参数,既可以输入功能,也可以输出功能 5.3-- ***mysql的变量*** -- 全局变量(内置变量):mysql数据库内置的变量 (所有连接都起作用) -- 查看所有全局变量: show variables -- 查看某个全局变量: select @@变量名 -- 修改全局变量: set 变量名=新值 -- character_set_client: mysql服务...
Assume we want to drop the UNIQUE constraint on the "Address" column, and the name of the constraint is "Con_First." To do this, we type in the following: MySQL: ALTER TABLE Customer DROP INDEX Con_First;Note that MySQL uses DROP INDEX for index-type constraints such as UNIQUE. ...
In MySQL, the syntax for ALTER TABLE Drop Column is, ALTER TABLE "table_name" DROP "column_name"; In Oracle, SQL Server, and Google BigQuery, the syntax for ALTER TABLE Drop Column is, ALTER TABLE "table_name" DROP COLUMN "column_name"; Let...
#Add Unique Constraint and Copy Unique Rows to Original Table To make sure there are no duplicates added in future, we can extend the previous set of queries to add aUNIQUEconstraint to the column. # Step1:CopydistinctvaluestotemporarytableCREATETEMPORARYTABLEtmp_user (SELECTid, nameFROMuserGROU...
Here Key_name is the unique constraint name. Now drop the unique constraint by the following command mysql> alter table test drop index id; The procedure is same to remove duplicate rows based on multiple column value. Here I show how to remove duplicate rows based on multiple columns ...
Error 'Cannot add or update a child row: a foreign key constraint fails故障解决 2016-06-12 16:46 −一大早的,某从库突然报出故障:SQL线程中断! 查看从库状态: mysql> show slave status\G Slave_IO_State: Waiting for master to send event Master_Log_File: mysql-bin.026023 R... ...
# No 'CASCADE' which works as a no-op in MySQL but is undocumented sql_delete_column = "ALTER TABLE %(table)s DROP COLUMN %(column)s" sql_delete_unique = "ALTER TABLE %(table)s DROP INDEX %(name)s" sql_create_column_inline_fk = ( ", ADD CONSTRAINT %(name)s FOREIGN KEY (%...
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