SQL语句问题

[niesen111]

（1）select gdRMJN_ZRZ from Project_SetGDRule_JN where ruleID='1802'显示原来的ZRZ

（2）select PJN_ZRZ,count(PJN_ZRZ) as Frequency from matchHistoryLog where MHL_matchState=1
and ruleID='1802' group by PJN_ZRZ 显示matchHistoryLog表中不同ZRZ出现的次数
要实现在显示matchHistoryLog表中不同ZRZ出现的次数的同时，显示对应的原来的ZRZ，该怎么写？

（3）select b.gdRMJN_ZRZ as PJN_OldKEY,a.PJN_ZRZ as PJN_NEWKEY,count(PJN_ZRZ) as Frequency from matchHistoryLog as a join Project_SetGDRule_JN as b on a.ruleID=b.ruleID and a.ruleID='1802'
and MHL_matchState=1 group by a.PJN_ZRZ,b.gdRMJN_ZRZ 计算的频度与（2）不同，求解释。

[黄_瓜]

selectb.gdRMJN_ZRZ as PJN_OldKEY,a.PJN_ZRZ as PJN_NEWKEY,count(PJN_ZRZ) as Frequency from 
(
select PJN_ZRZ,count(PJN_ZRZ) as Frequency from matchHistoryLog where MHL_matchState=1
) a,
Project_SetGDRule_JN as b
 on a.ruleID=b.ruleID

[-晴天]

两表连接后再统计,行数与原先的表会有不同,因为你是一对多.

当主表每一条记录都有子表的多条记录相对应,则行数会增多;
当主表每一条记录都与子表的一条记录相对应,则行数不变;
当主表中有大量的记录在子表中没有,而有的那些在子表中的记录数不多,则行数会减少.

[--小F--]

select
b.gdRMJN_ZRZ as PJN_OldKEY,a.PJN_ZRZ as PJN_NEWKEY,count(PJN_ZRZ) as Frequency from
(
select PJN_ZRZ,count(PJN_ZRZ) as Frequency from matchHistoryLog where MHL_matchState=1
) a join Project_SetGDRule_JN b
on a.ruleID=b.ruleID

[niesen111]

[Quote=引用 1 楼 beirut 的回复:]

SQL code
selectb.gdRMJN_ZRZ as PJN_OldKEY,a.PJN_ZRZ as PJN_NEWKEY,count(PJN_ZRZ) as Frequency from
(
select PJN_ZRZ,count(PJN_ZRZ) as Frequency from matchHistoryLog where MHL_matchState=1
) a,
Proj……
[/Quote]上述问题该如何解决？谢谢！

[niesen111]

[Quote=引用 3 楼 fredrickhu 的回复:]

select
b.gdRMJN_ZRZ as PJN_OldKEY,a.PJN_ZRZ as PJN_NEWKEY,count(PJN_ZRZ) as Frequency from
(
select PJN_ZRZ,count(PJN_ZRZ) as Frequency from matchHistoryLog where MHL_matchState=1
) a join Proje……
[/Quote]为什么会“提示RuleID无效”？

[-晴天]

[Quote=引用 4 楼 niesen111 的回复:]

引用 1 楼 beirut 的回复:

SQL code
selectb.gdRMJN_ZRZ as PJN_OldKEY,a.PJN_ZRZ as PJN_NEWKEY,count(PJN_ZRZ) as Frequency from
(
select PJN_ZRZ,count(PJN_ZRZ) as Frequency from matchHistoryLog where MHL……


上述问题该如何解决？谢谢！
[/Quote]

根据需求设计统计.