[2k5] 계산된 컬럼을 실제 저장하기(PERSISTED)

1. /**********************************************************************************************
   -- Title : [2k5] 계산된 컬럼을 실제 저장하기(PERSISTED)
   -- Reference : sqlworld.pe.kr
   -- Key word : persisted computed_columns is_persisted
   **********************************************************************************************/
   -- 읽을 때 계산됨
   create table ttt
   ( a int not null
   , b int not null
   , c as a+b
   );
   go
    
   insert into ttt values (1,1);
   insert into ttt values (2,2);
   go
    
   select * from ttt;
   go
    
   select * from sys.computed_columns where is_persisted=0 ;
   go
    
   -- 쓸 때 계산되어 저장
   create table ttt2
   ( a int not null
   , b int not null
   , c as a+b persisted   --// 실제 저장 명령
   );
   go
    
   insert into ttt2 values (1,1);
   insert into ttt2 values (2,2);
   go
    
   select * from ttt2;
   go