sql - Ms-Access 中的 IIF 语句

Question

我有这 3 张桌子：

我正在使用此代码将它们连接在一起（我使用的是 Delphi）：

ADOQ.SQL.Text := 'select a.IdArt as [Code d''Article], '+
                   'a.Nom,'+
                   'Str(a.Prix)+" TND" as Prix, '+
                   '(select Str(sum(QteEntree))+" "+a.unit from Stock where IdArt = a.IdArt group by IdArt) as [Quantite Entree],' +
                   '(select Str(sum(Qte))+" "+a.unit from Sold where IdArt = a.IdArt group by IdArt) as [Quantite Vendu],'+
                   'Str((select sum(QteEntree) from Stock where IdArt = a.IdArt group by IdArt) -' +
                   '(select sum(Qte) from Sold where IdArt = a.IdArt group by IdArt))+" "+a.unit as [Quantite Existe]'+

                   'from Article a ';

如您所见，当一个表中缺少一条记录时，它会将 Null 返回到 DbGrid，因此我想将丢失的记录替换为“0”。我试过这段代码：

ADOQ.SQL.Text := 'select a.IdArt as [Code d''Article], '+
                   'a.Nom,'+
                   'Str(a.Prix)+" TND" as Prix, '+
                   '(select Str(sum(QteEntree))+" "+a.unit from Stock where IdArt = a.IdArt group by IdArt) as [Quantite Entree],' +
                   '(select IIF( IsNull(sum(Qte)), "111" , Format( sum(Qte),"00.00") ) from Sold where IdArt = a.IdArt group by IdArt) as [Quantite Vendu],'+
                   'Str((select sum(QteEntree) from Stock where IdArt = a.IdArt group by IdArt) -' +
                   '(select sum(Qte) from Sold where IdArt = a.IdArt group by IdArt))+" "+a.unit as [Quantite Existe]'+

                   'from Article a ';

但没有任何改变，尽管这段代码运行良好：

ADOQ.SQL.Text := 'Select a.IdArt,IIF(( IsNull( s.qte) ), "00,00" , Format( (s.qte),"00.00") ) from Article a left join sold s on s.IdArt = a.IdArt';

我在这里做错了什么？

Answer 1

尝试取出“group by IdArt”部分 - 它们似乎没有必要，因为您已经在 WHERE 子句中排除了所有其他部分。

否则，这样的事情可能会改进您编写查询的方式：

select 
    a.IdArt as [Code d''Article], 
    a.Nom,
    Str(a.Prix)+" TND" as Prix, 
    Str(sum(stock.QteEntree))+" "+a.unit as [Quantite Entree],
    IIF( IsNull(sum(sold.Qte)), "111" , Format( sum(sold.Qte),"00.00") ) as [Quantite Vendu],
    Str(sum(stock.QteEntree) - sum(sold.Qte))+" "+a.unit as [Quantite Existe]

from Article a 
left join stock on a.IdArt = stock.IdArt
left join sold on a.IdArt = sold.IdArt
group by a.IdArt, a.Nom, a.Prix, a.unit

你可能需要调整它

实际上，我更愿意从上面写这个语句：

IIF( IsNull(sum(sold.Qte)), "111" , Format( sum(sold.Qte),"00.00") ) as [Quantite Vendu],

改为这样：

Format( sum( IIF( IsNull( sold.Qte ) , 0, sold.Qte ) ), "00.00" ) as [Quantite Vendu],

再次，我不能 100% 确定这会起作用，我只是在看你的函数的顺序和逻辑

Answer 2

好的，找到了解决方案：

iif( isnull((select sum(QteEntree) from Stock where IdArt = a.IdArt group by IdArt)) ,0, (select sum(QteEntree) from Stock where IdArt = a.IdArt group by IdArt) )