Question

我如何归档以下内容？

如果@chk = 0，则在结果中包括第4列，否则仅保留3列，如果选择了第4列，则该第4列需要左连接，并在分组依据中包括第4列

DECLARE @chk AS INT= 0;
SELECT a.Ledgerid, 
       b.LedgerCity,
       CASE WHEN @chk = 0 THEN SUM(a.TotalAmount) ELSE SUM(a.NetAmount) END,
       CASE WHEN @chk = 0 THEN c.ledgername END  (is it possilbe to completly do not have this column if @chk <> 0)
FROM ExpenseMaster A
     LEFT JOIN LedgerAddress AS B ON A.LedgerID = B.LedgerID
     LEFT JOIN LedgerMaster AS C ON A.LedgerID = C.LedgerID  --This left join is required only if @chk=0, same logic is there in above select statement
GROUP BY A.LedgerID, 
         B.LedgerCity;
         C.LedgerName; -- this 3rd group required only if @chk=0

一些帖子建议在分组依据中如何使用案例。我尝试了“ @ chk = 0时的情况，然后a.Ledgerid，b.Ledgercity，c.LedgerName否则a.Ledgerid，b.Ledgercity END进行分组；但这不起作用

Answer 1

使用IF .. ELSE块

IF @chk = 0 
BEGIN

SELECT a.Ledgerid, 
       b.LedgerCity,
       CASE WHEN @chk = 0 THEN SUM(a.TotalAmount) ELSE SUM(a.NetAmount) END,
       CASE WHEN @chk = 0 THEN c.ledgername END  
FROM ExpenseMaster A
     LEFT JOIN LedgerAddress AS B ON A.LedgerID = B.LedgerID
     LEFT JOIN LedgerMaster AS C ON A.LedgerID = C.LedgerID  --This left join is required only if @chk=0, same logic is there in above select statement
GROUP BY A.LedgerID, B.LedgerCity, C.LedgerName;


END
ELSE
BEGIN

SELECT a.Ledgerid, 
       b.LedgerCity,
       CASE WHEN @chk = 0 THEN SUM(a.TotalAmount) ELSE SUM(a.NetAmount) END    
FROM ExpenseMaster A
LEFT JOIN LedgerAddress AS B ON A.LedgerID = B.LedgerID
GROUP BY A.LedgerID, B.LedgerCity;


END

Answer 2

如果确定，数据库外部的任何人都无法运行查询并执行sql注入，只需使用简单的dynamic-sql语句

DECLARE @sql AS NVARCHAR(MAX);
DECLARE @chk AS INT= 0;

set @sql = N'SELECT a.Ledgerid, 
               b.LedgerCity, ' +
               CASE WHEN @chk = 0 THEN 'SUM(a.TotalAmount) ' ELSE 'SUM(a.NetAmount) ' END +
               CASE WHEN @chk = 0 THEN ', c.ledgername ' ELSE ' ' END +
        'FROM ExpenseMaster A
             LEFT JOIN LedgerAddress AS B ON A.LedgerID = B.LedgerID ' +
             CASE WHEN @chk=0 THEN 'LEFT JOIN LedgerMaster AS C ON A.LedgerID = C.LedgerID ' ELSE '' END +
        'GROUP BY A.LedgerID, 
                 B.LedgerCity' +
                 CASE WHEN @chk = 0 THEN ', C.LedgerName;' ELSE ';' END;

exec sp_executesql @sql

选择，左联接和分组依据时的情况

2 个答案: