SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '07', a.factration)) AS JUL,
SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '08', a.factration)) AS AGU,
SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '09', a.factration)) AS SEP,
SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '10', a.factration)) AS OCT,
SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '11', a.factration)) AS NOV,
SUM(decode(TO_CHAR(a.telfeedate, 'mm'), '12', a.factration)) AS DEC
FROM (SELECT a.userper, a.tel, a.standfee, b.telfeedate, b.factration
FROM TELFEESTAND a, TELFEE b
WHERE a.tel = b.telfax) a
GROUP BY a.userper, a.tel, a.standfee, TO_CHAR(a.telfeedate, 'yyyy')
说明：四表联查问题：
| SQL: select * from a left inner join b on a.a=b.b right inner join c on a.a=c.c inner join d on a.a=d.d where ..... |
说明：得到表中最小的未使用的ID号
SQL:
| SELECT (CASE WHEN EXISTS(SELECT * FROM Handle b WHERE b.HandleID = 1) THEN MIN(HandleID) 1 ELSE 1 END) as HandleID FROM Handle WHERE NOT HandleID IN (SELECT a.HandleID - 1 FROM Handle a) |
2.删除重复数据
一、具有主键的情况
a.具有唯一性的字段id(为唯一主键)
| delete table where id not in ( select max(id) from table group by col1,col2,col3... ) |
group by 子句后跟的字段就是你用来判断重复的条件，如只有col1，那么只要col1字段内容相同即表示记录相同。
b.具有联合主键
假设col1 ',' col2 ','...col5 为联合主键
| select * from table where col1 ',' col2 ','...col5 in ( select max(col1 ',' col2 ','...col5) from table where having count(*)＞1 group by col1,col2,col3,col4 ) |
group by 子句后跟的字段就是你用来判断重复的条件，如只有col1，那么只要col1字段内容相同即表示记录相同。
c:判断所有的字段
| select * into #aa from table group by id1,id2,.... delete table insert into table select * from #aa |
二、没有主键的情况
a:用临时表实现
| select identity(int,1,1) as id,* into #temp from ta delete #temp where id not in ( select max(id) from # group by col1,col2,col3... ) delete table ta inset into ta(...) select ..... from #temp |
b:用改变表结构（加一个唯一字段）来实现
| alter table 表 add newfield int identity(1,1) delete 表 where newfield not in ( select min(newfield) from 表 group by 除newfield外的所有字段 ) alter table 表 drop column newfield |
文章整理：西部数码--专业提供域名注册、虚拟主机服务
http://www.west263.com
以上信息与文章正文是不可分割的一部分,如果您要转载本文章,请保留以上信息，谢谢!
