SQL> SELECT owner,constraint_name,constraint_type,table_name,status,deferrable,validated 2 FROM user_constraints 3 WHERE table_name = 'TB_CONSTRAINT_3'; OWNER CONSTRAINT_NAME C TABLE_NAME STATUS DEFERRABLE VALIDATED --- --- - --- --- --- --- ROBINSON PK_TB_CONS3_EMPNO_ENAME P TB_CO...
ROBINSON PK_TB_CONS3_EMPNO_ENAME P TB_CONSTRAINT_3 ENABLED NOT DEFERRABLE VALIDATED ROBINSON SYS_C005554 U TB_CONSTRAINT_3 ENABLED NOT DEFERRABLE VALIDATED --两列上具有相同的约束名 SQL> SELECT * FROM user_cons_columns WHERE table_name = 'TB_CONSTRAINT_3'; OWNER CONSTRAINT_NAME TABLE_NAME ...
We cannot remove this column until it has a dependent object in it. To remove this column, first, remove the dependency and then delete the column. 在此列中有从属对象之前,我们无法删除它。 要删除此列,请首先删除依赖项,然后删除该列。 ALTER TABLE [dbo].[ProductSales] DROP CONSTRAINT ck_price...
In Oracle, SQL Server, and Google BigQuery, the syntax for ALTER TABLE Drop Column is, ALTER TABLE "table_name" DROP COLUMN "column_name"; Let's look at the example. Assuming our starting point is the Customer table created in the CREATE TABLE section: Table Customer ...
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. ...
--SQL基础--> 约束(CONSTRAINT) --=== 一、几类数据完整性 实体完整性:表中记录不反复(不论什么两条记录不全等)而且每条记录都有一个非空主键 域完整性:表中字段值必须与字段数据类型、格式、有效范围相吻合 參照完整性:不能引用不存在的值 自己定义...
有时候我们在drop column的时候,会遇到一些default constraints而不能drop,如果我们已经知道constraint name,则可以用下面的语句先把constraint remove掉,然后再drop column。 declare@sqlnvarchar(1024) set@sql=N'alter table [system] drop constraint DF_system_LastGraceDate' ...
Now we drop the IS_REGUAL column from the table, which has a default constraint as below. EXEC SP_HELP STUDENT_DETAILS SQL Copy Now if we drop the column by using the below query alter table STUDENT_DETAILS drop column IS_REGULAR SQL Copy Then we will face the below error. Now we ...
Then go back and delete the column. The same error is generated executing the T-SQL. -- attempt to drop column EmployeeStatusID from EmployeesALTERTABLE[dbo].[Employees]DROPCOLUMN[EmployeeStatusID]GO First, drop the key with an ALTER TABLE DROP CONSTRAINT and then drop the column with an ...
[ CONSTRAINT constraint_name ] { [ NULL | NOT NULL ] { PRIMARY KEY | UNIQUE } [ CLUSTERED | NONCLUSTERED ] [ WITH FILLFACTOR = fillfactor ] [ WITH ( index_option [, ...n ] ) ] [ ON { partition_scheme_name (partition_column_name) | filegroup | "default" } ] | [ FOREIGN K...