SQL语句汇总(一)

转自: http://www.cnblogs.com/HondaHsu/archive/2007/06/22/792856.html
1.查询记录相同的其中一笔记录

SELECT mat12id, mat12name , bat22id,PRICE

FROM (SELECT mat12id, mat12name , bat22id,PRICE,

ROW_NUMBER() OVER (PARTITION BY mat12id ORDER BY bat22id DESC) RN

FROM bat22)

WHERE RN = 1

2.查询从多少行到多少行的记录

SELECT * FROM

(SELECT A.*, rownum
r FROM ( SELECT * FROM TableName )A WHERE rownum <90 ) B

WHERE r > 70

或者:

select a,b,c,d from (select a,b,c,d from T order by c) where rownum<=30

minus

select a,b,c,d from (select a,b,c,d from T order by c) where rownum <=20;

3.实现分组（小计，合计）

•DEPTNO EMPNO ENAME TOTAL_SAL
•---------- ----- ---------- ----------

•10 7782 CLARK 2450
•10 7839 KING 5000
•小计
7450
•20 7566 JONES 2975
•20 7788 SCOTT 3000
•20 7902 FORD 3000
•小计 8975
•30 7698 BLAKE 2850
•小计 2850
•合计 19275

SQL如下:

SELECT CASE

WHEN a.deptno IS NULLTHEN '合计'

WHEN a.deptno IS NOT NULL AND a.empno IS NULLTHEN '小计'

ELSE '' || a.deptno

END deptno,a.empno,a.ename, SUM(a.sal) total_sal

FROM scott.emp a

WHERE a.sal > 2000

GROUP BY GROUPING SETS[/u]((a.deptno),(a.deptno, a.empno, a.ename),());

4.行列转换

•数据格式一
•CARD_CODE Q BAL
•--------- ---------- ----------

•001 1 27
•001 2 10
•001 3 36
•001 4 97
•002 1 96
•002 2 12
•002 3 15
•002 4 32

•数据格式二
•CARD_CODE Q1 Q2 Q3 Q4
•--------- ---------- ---------- ---------- ----------
•001 27 10 36 97
•002 96 12 15 32



从格式一到格式二



SELECT a.card_code,

SUM(decode(a.q, 1, a.bal, 0)) q1,SUM(decode(a.q, 2, a.bal, 0)) q2,

SUM(decode(a.q, 3, a.bal, 0)) q3,SUM(decode(a.q, 4, a.bal, 0)) q4

FROM t_change_lc a

GROUP BY a.card_code

ORDER BY 1;

5. Order By



select * from courses union select * from minors order by 1 对第一个字段进行升序排序

select * from courses union select * from minors order by desc 错误,加个表中存在(或转换过后的)的字段名(或转换过后的)

例如

select * from courses union select * from minors order by id desc select substr(id , 1 , 2) new_id, * from courses union select * from minors order by substr(id , 1 , 2) desc

ORDER BY 1 表示 所select 的字段按第一个字段排序

ORDER BY ASC应该没有这样写法,ORDER BY 后面不是字段就是数字,

可以ORDER BY 1 ASC 或者ORDER BY COL1 ASC

ASC表示按升序排序,DESC表示按降序排序

转自; http://blog.csdn.net/lingxyd_0/article/details/2653187
--先看一下例子

SQL> select * from test_tab order by 1;

COL_A COL_B

---------- ----------

A 1

A 2

B 2

B 3

C 4

D 1

D 12

D 121

D 12

9 rows selected

SQL> select * from test_tab order by 2;

COL_A COL_B

---------- ----------

A 1

D 1

A 2

B 2

B 3

C 4

D 12

D 12

D 121

9 rows selected

SQL> select * from test_tab order by 3;

select * from test_tab order by 3

ORA-01785: ORDER BY 项必须是 SELECT-list 表达式的数目

以上看来:1表示第一个栏位,2表示第二栏位 依此类推

当表中只有2个栏位时,ORDER BY 3就会出错