时间戳

首页 > 解决方案 > Select, Left Join 和 Group By 中的情况

sql - Select, Left Join 和 Group By 中的情况

问题描述

我如何归档以下内容？

如果@chk = 0，则在结果中包含第 4 列，否则仅保留 3 列，如果选择了第 4 列，则第 4 列需要左连接，并将第 4 列包含在 group by

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 Group by 中如何使用案例。我尝试了“当@chk=0 然后a.Ledgerid,b.Ledgercity,c.LedgerName else a.Ledgerid,b.Ledgercity END; 时分组；但这没有用

标签： sqlsql-server

解决方案

如果您确定，数据库外部的任何人都无法运行您的查询并执行 sql-injection，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

推荐阅读