删除constraint为变量名的约束

 1 create procedure DropPK_MESSAGEUSERS
 2 as
 3 begin
 4 declare @pk_name varchar(100) 
 5 SELECT @pk_name=CONSTRAINT_NAME 
 6 from INFORMATION_SCHEMA.TABLE_CONSTRAINTS 
 7 WHERE CONSTRAINT_NAME like ‘%messageusers%‘ and 
 8 CONSTRAINT_TYPE=‘primary KEY‘  
 9 exec(‘alter table [MESSAGEUSERS] drop constraint ‘+ @pk_name)
10 end