--check --constraint 表名; --go --添加check约束描述 execute sp_addextendedproperty N'MS_Description', N'约束描述', N'SCHEMA', N'dbo', N'TABLE', N'表名', N'CONSTRAINT', N'约束名'; go 示例: --修改check约束 use testss go --如果约束存在则先删除 if exists(select * from sysobjects...
if exists(select * from sysobjects where name=约束名) alter table 表名 drop constraint 约束名; go alter table 表名 add constraint 约束名 check(约束规则),constraint 约束名 check(约束规则); go 示例: -- 添加一个默认约束 use testss; go if exists(select * from sysobjects where name='check1...
alter table 表名 add constraint 约束名 check(约束规则),constraint 约束名 check(约束规则); go 示例: -- 添加一个默认约束 use testss; go if exists(select * from sysobjects where name='check1') alter table test1 drop constraint check1; go alter table test1 add constraint check1 check(height...
DBCC CHECKCONSTRAINTSisn't guaranteed to findallconstraint violations. If a single row violates multiple constraints, only theWHEREclause for the first violation is listed. Unless another row exists with the same combination of values that produce the violation, and has that violation as the f...
Note:TheCHECKconstraint is used to validate data while insertion only. To check if the row exists or not, visitSQL EXISTS. Example 1: SQL CHECK Constraint Success -- apply the CHECK constraint to the amount columnCREATETABLEOrders (
SQL Server/Oracle/MS Access: ALTER TABLE Persons DROP CONSTRAINT chk_Person MySQL: ALTER TABLE Persons DROP CHECK chk_Person 2.SQL DEFAULT约束 DEFAULT约束用于向列中插入默认值。 如果没有规定其他的值,那么会将默认值添加到所有的新纪录 实例: ...
删除约束的语法如下：Alter Table 表名Drop Constraint 约束名附加：在创建表的时候同时添加约束的写法:use stuDBgoif exists(select * from Sysobjects where name = 'stuInfo')drop table stuInfogocreate table stuInfo(stuName varchar(20) not null primary key(stuName)，stuID int not null ...
向表或列附加 CHECK 约束时,必须包括 SQL 表达式。 在提供的框中键入 CHECK 约束表达式。UI 元素列表表达式 输入表达式您可以创建简单的约束表达式,用简单条件检查数据;也可以使用布尔运算符创建复杂表达式,用若干个条件检查数据。 例如,假设 Authors 表有一个需要 5 位数字字符串的邮政编码列。 ...
DBCC CHECKCONSTRAINTSisn't guaranteed to findallconstraint violations. If a single row violates multiple constraints, only theWHEREclause for the first violation is listed. Unless another row exists with the same combination of values that produce the violation, and has that violation as the first ...
We have a table dbo.ItemDetail with a check constraint . IF NOT EXISTS( SELECT 1 FROM sys.tables WHERE Name = N’ItemDetail’ AND SCHEMA_NAME( SCHEMA_ID ) = N’dbo’ ) BEGIN CREATE TABLE [dbo].[ItemDetail] ( [Id] [INT] NOT NULL, ...