SQL Server code sets the primary key and automatically grows

Create a new data table, set UserID as the primary key and automatically grow

CREATE TABLE T_userlogin (UserId int NOT null primary key identity (1,1), UserName nvarchar (m) not null,pass varchar () NULL)

Modify a data table that has been built, set UserID as the primary key and grow automatically

ALTER TABLE TB ALTER COLUMN ID int NOT NULL

ALTER TABLE TB ADD constraint Pkid primary key (ID)

Delete primary key

Declare @Pk VarChar (100);

Select @Pk =name from sysobjects where parent_obj=object_id (' TB ') and xtype= ' Pk ';

If @Pk is not null

EXEC (' Alter table TB Drop ' + @Pk)