sql - SQL 查询连接

Question

我有以下数据集:

ID   PeriodID    Account     Amount  
1    1000        Y0001       100.00  
2    1000        M0001       20.00  
3    1000        Y0002       75.00  
4    1000        M0002       15.00  
5    1000        Y0003       100.00  
6    1000        Y0004       200.00  

我需要编写一个查询，只要存在“Y”帐户而没有“M”帐户，则返回零，例如:

PeriodID    Account     Amount  
1000        Y0001       100.00  
1000        M0001       20.00  
1000        Y0002       75.00  
1000        M0002       15.00  
1000        Y0003       100.00  
1000        Y0003       0.00  
1000        Y0004       200.00 
1000        Y0004       0.00 

有什么建议吗？

Answer 1

也许不是最有效的方法，但这应该可以满足您的需求:

SELECT PeriodID, Account, Amount
FROM myTable

UNION ALL

SELECT PeriodID, Account, 0.00 AS Amount
FROM myTable A
WHERE NOT EXISTS (
    SELECT * FROM myTable B 
    WHERE B.Account = 'M' + SUBSTRING(A.Account, 2, LEN(A.Account) - 1)
)