是否可以连接具有不同字段值的两个表？我正在使用MS SQL Server 2008。
表A（original image，感谢@EdwardRusu将图像翻译成文本）：
+ ----- + --------- + -------- + ----------- + ------------------ + ---------------- + ----------- +
| RecID | Member ID | LoanType | LoanSubType | Application Number | Application Date | Loan Amount |
+ ----- + --------- + -------- + ----------- + ------------------ + ---------------- + ----------- +
| 3 | 00005 | Regular | | 201604002 | 2016-02-28 | 39864.00 |
| 185 | 00005 | Special | Special ... | 201604183 | 2016-10-31 | 10000.00 |
| 318 | 00005 | Regular | | 201605063 | 2016-05-18 | 39864.00 |
| 427 | 00005 | Regular | | 201608021 | 2016-08-18 | 39872.00 |
| 486 | 00005 | Special | Special ... | 201609044 | 2016-09-07 | 10000.00 |
| 589 | 00005 | Regular | | 201611008 | 2016-11-04 | 39872.00 |
| 689 | 00005 | Regular | | 201702004 | 2017-02-02 | 39872.00 |
+ ----- + --------- + -------- + ----------- + ------------------ + ---------------- + ----------- +
表B（original image）：
+ --------------- + --------- + ------ + ----- + ---------- + -------- + -------- + -------- +
| ProjectAcctCode | Member ID | TMonth | TYear | TLastDate | TDebit | TCredit | TBalance |
+ --------------- + --------- + ------ + ----- + ---------- + -------- + -------- + -------- +
| 105350500 | 00005 | 1 | 2017 | 2017-01-31 | 0.00 | 2952.00 | -2952.00 |
| 105350500 | 00005 | 5 | 2016 | 2016-05-31 | 73084.00 | 33220.00 | 39864.00 |
| 105350500 | 00005 | 6 | 2016 | 2016-06-30 | 0.00 | 2951.42 | -2952.42 |
| 105350500 | 00005 | 7 | 2016 | 2016-07-31 | 0.00 | 3014.14 | -3014.14 |
| 105350500 | 00005 | 8 | 2016 | 2016-08-31 | 39872.00 | 33905.26 | 5973.55 |
| 105350500 | 00005 | 9 | 2016 | 2016-09-30 | 0.00 | 2952.00 | -2952.00 |
| 105350500 | 00005 | 10 | 2016 | 2016-10-31 | 0.00 | 3014.73 | -3014.73 |
| 105350500 | 00005 | 11 | 2016 | 2016-11-30 | 39872.00 | 33905.26 | 5966.74 |
| 105351000 | 00005 | 1 | 2017 | 2017-01-31 | 0.00 | 975.03 | -975.03 |
| 105351000 | 00005 | 5 | 2016 | 2016-05-31 | 5000.00 | 1000.00 | 4000.00 |
| 105351000 | 00005 | 6 | 2016 | 2016-06-30 | 0.00 | 1000.00 | -1000.00 |
| 105351000 | 00005 | 7 | 2016 | 2016-07-31 | 0.00 | 1000.00 | -1000.00 |
| 105351000 | 00005 | 8 | 2016 | 2016-08-31 | 0.00 | 1000.00 | -1000.00 |
| 105351000 | 00005 | 9 | 2016 | 2016-09-30 | 10000.00 | 1000.00 | 9000.00 |
| 105351000 | 00005 | 10 | 2016 | 2016-10-31 | 0.00 | 955.82 | -955.82 |
| 105351000 | 00005 | 11 | 2016 | 2016-11-30 | 0.00 | 965.38 | -965.38 |
+ --------------- + --------- + ------ + ----- + ---------- + -------- + -------- + -------- +
我想通过MemberID，LoanType，ApplicationNo，ApplicationDate来分组TableB中的TBalance。应该基于LoanType和ProjAcctCode AND ApplicationDate和TLastDate连接这两个表。 LoanType和ProjAcctCode具有不同的值。但是，“REGULAR”Loantype等于“105350500”ProjAcctCode，“SPECIAL LoanType”相当于“105351000”ProjAcctCode。 ApplicationDate应小于或等于TLastDate。
因此，如果我将为“REGULAR”贷款类型生成记录，我应该有这样的事情（original image）：
+ -------- + -------- + ------------- + --------------- + ---------- + ------------ + --------- + --------- +
| MemberID | LoanType | ApplicationNO | ApplicationDate | LoanAmount | ProjAcctCode | TLastDate | Balance |
+ -------- + -------- + ------------- + --------------- + ---------- + ------------ + --------- + --------- +
| 000005 | Regular | 201608021 | 8/18/2016 | 39,872.00 | 105350500 | 8/31/2016 | 39,871.44 |
+ -------- + -------- + ------------- + --------------- + ---------- + ------------ + --------- + --------- +
但是我的查询
SELECT a.MemberID,
(SELECT TOP (1) ApplicationNo
FROM TABLE A
WHERE (MemberID = a.MemberID) AND (ApplicationDate <= b.TLastDate)
ORDER BY ApplicationNo DESC) AS ApplicationNo,
(SELECT TOP (1) LoanAmount
FROM TABLE A AS SAL_APPLICATION_HEADER_1
WHERE (MemberID = a.MemberID) AND (ApplicationDate <= b.TLastDate)
ORDER BY ApplicationNo DESC) AS LoanAmount,
(SELECT TOP (1) ApplicationDate
FROM TABLE A AS SAL_APPLICATION_HEADER_2
WHERE (MemberID = a.MemberID)
AND (ApplicationDate <= b.TLastDate)
ORDER BY ApplicationNo DESC) AS ApplicationDate,
vwSAL_Balance_SL_1.ProjAcctCode,
b.TDebit,
b.TCredit,
b.TBalance AS Balance,
b.TLastDate
FROM TABLE A AS a
INNER JOIN TABLE B AS b ON a.MemberID = b.SLCode
GROUP BY a.MemberID,
b.TDebit,
b.TCredit,
b.TBalance,
b.ProjAcctCode,
b.TLastDate
HAVING (a.MemberID = N'00005') AND (b.TLastDate = '8/31/2016')
我得到了这个结果（original image）：
+ -------- + ------------- + ---------- + --------------- + ------------ + -------- + -------- + -------- + ---------- +
| MemberID | ApplicationNo | LoanAmount | ApplicationDate | ProjAcctCode | TDebit | TCredit | Balance | TLastDate |
+ -------- + ------------- + ---------- + --------------- + ------------ + -------- + -------- + -------- + ---------- +
| 00005 | 201608021 | 39872.00 | 2016-08-18 | 105351000 | 0.00 | 1000.00 | -1000.00 | 2016-08-31 |
| 00005 | 201608021 | 39872.00 | 2016-08-18 | 105350500 | 39872.00 | 33898.45 | 5973.55 | 2016-08-31 |
+ -------- + ------------- + ---------- + --------------- + ------------ + -------- + -------- + -------- + ---------- +
这可能太长但请求帮助。谢谢。
答案 0 :(得分：0)
tl; dr 是的，有可能。最后的查询块将为您提供所需的内容。
是的，只要您知道两者之间存在某种相关性，就可以连接两个具有不同字段值的表。我将引导您完成连接语句的构造，该语句可以为您提供所需的内容。你需要三件事：
1）匹配MemberID和SLCode
2）匹配LoanType和ProjAcctCode
3）匹配日期
MemberID和SLCode
根据您上面的评论，我将假设SLCode与B中的MemberID相同。
select *
from A
inner join B
on B.MemberID = A.MemberID -- or B.SLCode = A.MemberID
LoanType和ProjAcctCode
在此示例中，您希望在连接中使用case语句，例如
inner join B.ProjAcctCode = case A.LoanType when 'Regular' then 105350500 else 105351000 end
这表示如果LoanType是Regular，则只加入具有ProjAcctCode = 105350500的记录;否则加入具有ProjAcctCode 105351000的记录。（这里，LoanType只有两个状态，所以使用else子句捕获特殊贷款是完全没问题。如果有两个以上的状态，那么你必须使用其他条件。）
select *
from A
inner join B
on B.MemberID = A.MemberID
and B.ProjAcctCode = case A.LoanType when 'Regular' then 105350500 else 105351000 end
<强>日期
立即过滤日期过滤器。
select *
from A
inner join B
on B.MemberID = A.MemberID
and B.ProjAcctCode = case A.LoanType when 'Regular' then 105350500 else 105351000 end
and A.ApplicationDate <= B.TLastDate
群组和汇总
现在您已正确连接表，您只需要进行分组和聚合。您可以对A中的任何内容进行分组，因为这些字段不会针对您想要的聚合进行更改，而您只需要对如何选择来自B的内容有点聪明。在您的问题中，它看起来像您想要的ProjAcctCode（这不会改变，因此我们也可以对此进行分组），TLastDate（这确实会改变，因此我们需要在某些条件上进行聚合）和TBalance（我们希望从中得到总和）。我假设您需要最新的TLastDate，因此您的查询将类似于
select A.MemberID,
A.LoanType,
A.ApplicationNumber,
A.ApplicationDate,
[anything else you want from A],
B.ProjAcctCode -- aggregate not needed because this doesn't change
max(B.TLastDate) as TLastDate,
sum(B.TBalance) as TBalance
from A
inner join B
on B.MemberID = A.MemberID
and B.ProjAcctCode = case A.LoanType when 'Regular' then 105350500 else 105351000 end
and A.ApplicationDate <= B.TLastDate
group by A.MemberID,
A.LoanType,
A.ApplicationNumber,
A.ApplicationDate,
[anything else you selected from A],
B.ProjAcctCode
这将产生下表
+ -------- + -------- + ----------------- + --------------- + ------------ + ---------- + -------- +
| MemberID | LoanType | ApplicationNumber | ApplicationDate | ProjAcctCode | TLastDate | TBalance |
+ -------- + -------- + ----------------- + --------------- + ------------ + ---------- + -------- +
| 00005 | Regular | 201604002 | 2016-02-08 | 105350500 | 2017-01-31 | 36913.19 |
| 00005 | Special | 201604183 | 2016-10-31 | 105351000 | 2017-01-31 | -2896.23 |
| 00005 | Regular | 201605063 | 2016-05-18 | 105350500 | 2017-01-31 | 36913.19 |
| 00005 | Regular | 201608021 | 2016-08-18 | 105350500 | 2017-01-31 | 3014.75 |
| 00005 | Special | 201609044 | 2016-09-07 | 105351000 | 2017-01-31 | 6103.77 |
| 00005 | Regular | 201611008 | 2016-11-04 | 105350500 | 2017-01-31 | 3014.74 |
+ -------- + -------- + ----------------- + --------------- + ------------ + ---------- + -------- +
注意：ApplicationNumber 201702004的贷款不会出现在最终结果中，因为它按日期过滤掉（即其申请日期大于B中的所有TLastDate）。
答案 1 :(得分：0)
我只是在查询中使用UNION（每个LoanType）来获得所需的结果。