修改主键的SQL

declare @defname varchar(100)
declare @cmd varchar(500)
declare @tablename varchar(100)
declare @keyname varchar(100)

Set @tablename='Temp1'
Set @keyname='id,name,js' --需要設置的key,分隔

select @defname= name
   FROM sysobjects so
   JOIN sysconstraints sc
   ON so.id = sc.constid
   WHERE object_name(so.parent_obj) = @tablename

if @defname is not null
begin
select @cmd='alter table '+ @tablename+ ' drop constraint '+ @defname
   if @cmd is null print 'No default constraint to drop'
   exec (@cmd)
 end
else
 set @defname='PK_'+@keyname

select @cmd='alter table '+ @tablename+ ' ADD constraint '+ @defname +' PRIMARY KEY CLUSTERED('+@keyname+')'
   exec (@cmd)