如何把exists 转成 not exists 达到同样的效果？
CREATE   TABLE   table1(
        co1     varchar   (100))
            CREATE   TABLE   table2(
        co2     varchar   (100))
        INSERT   INTO   table1   (co1)   VALUES( 'abc ')
  INSERT   INTO   table1   (co1)   VALUES( 'abc ')
    INSERT   INTO   table1(co1)   VALUES( 'aab ')
        INSERT   INTO   table1   (co1)   VALUES( 'bbc ')
-------如何把exists   转成   not   exists   达到同样的效果？
        IF   EXISTS   (SELECT   1   FROM   table1   WHERE   table1.co1   NOT   IN   (SELECT   *   FROM   table2))
        BEGIN
       
        INSERT   INTO   table2   (co2)   SELECT   DISTINCT   co1   FROM   table1   WHERE   table1.co1   NOT   IN   (SELECT   *   FROM   table2)
        END  


------解决方案--------------------
CREATE TABLE table1(co1 varchar(100))
CREATE TABLE table2(co2 varchar(100))

INSERT INTO table1 select 'abc '
union all select 'aab '
union all select 'bbc '
union all select 'dub '
union all select '1ub '

INSERT INTO table2 select 'dub '
union all select 'aab '

select * from table1
select * from table2

IF not EXISTS(select 1 from table1 a inner join table2 b on a.co1=b.co2 group by a.co1 having(count(distinct a.co1)=(select count(distinct co1) from table1)))
BEGIN
INSERT INTO table2(co2) SELECT DISTINCT co1 FROM table1 WHERE co1 NOT IN (SELECT co2 FROM table2)
END

select * from table2

drop table table1,table2