ALTER TABLE Persons DROP PRIMARY KEY 但对于 SQL Server / Oracle / MS Access, 一个列 ALTER TABLE Persons DROP CONSTRAINT P_Id 若起约束名,也可如下多个列 ALTER TABLE Persons DROP CONSTRAINT pk_PersonID 11、SQL FOREIGN KEY 约束 一个表中的 FOREIGN KEY 指向另一个表中的 UNIQUE KEY(唯一约束的...
drop table 表名 表的清单存放在该库的系统表sysobjects中 demo: usetext_datagoifexists(select*fromsysobjectswherename='textinfo')--检测textinfo表是否存在droptabletextinfo--删除表textinfocreatetabletextinfo--创建表textinfo( Tidintidentity(1,1)primarykeynotnull,--主键、标识列订、不可为空Tinfonvarchar(200...
drop constraint PK_uinfor; -- 方法二(删除原主键) if exists(select * from sysobjects where xtype='PK' and parent_obj=object_id(N'uinfor') ) begin --使用动态语句可以保证无论主键名是怎么定义都可以正常删除 declare @s nvarchar(4000) select @s=N'alter table uinfor drop constraint'+quotenam...
DROP TABLE IF EXISTS dbo.Emp; GO CREATE TABLE dbo.emp ( empid INT NOT NULL CONSTRAINT PK_emp_empid PRIMARY KEY, mgrid INT NULL CONSTRAINT FK_emp_empid REFERENCES dbo.emp, empname VARCHAR(25) NOT NULL, jobtitle VARCHAR(25) NOT NULL, salary int NOT NULL, CHECK (empid <> mgrid) ); ...
DROP TABLE IF EXISTS dbo.Emp; GO CREATE TABLE dbo.emp ( empid INT NOT NULL CONSTRAINT PK_emp_empid PRIMARY KEY, mgrid INT NULL CONSTRAINT FK_emp_empid REFERENCES dbo.emp, empname VARCHAR(25) NOT NULL, jobtitle VARCHAR(25) NOT NULL, ...
Alter Table Add Column if Not Exists to update Schema Modification Script Alter Table add Column - How do you add a column after say the second column Alter table add constraint primary key clustered identity(1,1) ALTER TABLE ALTER COLUMN (To set the default value) ALTER TAB...
constraint violation occurs.SETXACT_ABORTON;BEGINTRYBEGINTRANSACTION;-- A FOREIGN KEY constraint exists on this table. This-- statement will generate a constraint violation error.DELETEFROMProduction.ProductWHEREProductID =980;-- If the DELETE statement succeeds, commit the transaction.COMMITTRANSACTION;...
Alter Table Add Column if Not Exists to update Schema Modification Script Alter Table add Column - How do you add a column after say the second column Alter table add constraint primary key clustered identity(1,1) ALTER TABLE ALTER COLUMN (To set the default value) ALTER TABLE Progress? ALT...
Subclause 11.26, "<drop table constraint definition>": <drop table constraint definition> ::= DROP CONSTRAINT <constraint name> <drop behavior> ... Conformance Rules Without Feature F381, "Extended schema manipulation", conforming SQL language shall not contain a <drop table constraint defi...
2.1.2.58 F381-03, ALTER TABLE statement: DROP CONSTRAINT clause 2.1.2.59 F383, Set column not null clause 2.1.2.60 F384, Drop identity property clause 2.1.2.61 F385, Drop column generation expression clause 2.1.2.62 F386, Set identity column generation clause 2.1.2.63 F392, ...