sql寫法小記

create table t1(a int,b int);
/
create table t2(a int,b int);
/
create table t3(a int,b int);
/
insert into t2 values(1,1);
/
insert into t2 values(2,2);
/
insert into t3 values(3,3);
/
insert into t3 values(4,4);
/

insert into t1(a,b)
values(
             (select a from t2 where rownum=1),
             (select b from t3 where rownum=1)
            );


小記：１，values內的子查詢只能適用於返回單行單行值
             2,   values內的子查詢的select列只是單個列，而不能是多行