选择表中的某一行记录:(理解:rownum是oracle系统顺序分配为从查询返回的行的编号) select * from (select rownum a,t.* from testtab t) where a=2; select * from (select rownum a,t.* from testtab t) where a=3; select * from (select rownum a,t.* from testtab t) where a=4; 不能为: select * from (select rownum,t.* from testtab t) where rownum=2;或 select * from testtab where rownum=2; 返回多行记录: select * from testtab where rownum<=10; 返回某段记录:(如取记录表中4-10行) select * from (select rownum no,testtab.* from testtab where rownum<=10) where no>=4; 不能为: select * from tsettab where rownum>10; 返回最后一行记录: select * from (select rownum a,t.* from testtab t) where a=(select count(*) from testtab);
选记录用rownum就行了,楼上讲的不错
1、select * from tab where rownum<1001; 2、select count(*) from tab;
select * from (select rownum a,t.* from testtab t) where a=2;
select * from (select rownum a,t.* from testtab t) where a=3;
select * from (select rownum a,t.* from testtab t) where a=4;
不能为:
select * from (select rownum,t.* from testtab t) where rownum=2;或
select * from testtab where rownum=2;
返回多行记录:
select * from testtab where rownum<=10;
返回某段记录:(如取记录表中4-10行)
select * from (select rownum no,testtab.* from testtab where rownum<=10) where no>=4;
不能为:
select * from tsettab where rownum>10;
返回最后一行记录:
select * from (select rownum a,t.* from testtab t) where a=(select count(*) from testtab);
2、select count(*) from tab;
FROM t
SAMPLE (100*1000/50000)