Question

如何向查询添加其他WHERE子句。有这个疑问：

SELECT round(Sum(Zarada), 2) AS Zarada, 
       cms_cart_customers.Firstname,
       cms_cart_wallet.WalletType as WW ,
       cms_cart_customers.Lastname, 
       FROM_UNIXTIME(`cms_cart_customers`.`d_ins`, " %d.%m.%Y") AS Datum_formatiran 
  FROM (cms_cart_customers) 
  LEFT JOIN cms_cart_wallet
    ON cms_cart_wallet.IdBuyer =cms_cart_customers.Id 
  WHERE `cms_cart_customers`.`IDReferral` = '199' AND
        if(ww = 7) THEN ' cms_cart_wallet.WalletType =7' END IF 
  GROUP BY cms_cart_customers.Id

如果选择cms_cart_wallet.WalletType为Ww则添加新的附加子句WHERE cms_cart_wallet.WalletType为7。有可能以这种方式做到吗???

Answer 1

您可以通过在左连接中添加一个子句来实现此目的，条件如下所示。

SELECT round(Sum(Zarada), 2) AS Zarada, cms_cart_customers.Firstname,cms_cart_wallet.WalletType as WW ,cms_cart_customers.Lastname, FROM_UNIXTIME(cms_cart_customers.d_ins, " %d.%m.%Y") AS Datum_formatiran FROM (cms_cart_customers) LEFT JOIN cms_cart_wallet ON cms_cart_wallet.IdBuyer =cms_cart_customers.Id and cms_cart_wallet.WalletType =7 WHERE cms_cart_customers.IDReferral = '199'  GROUP BY cms_cart_customers.Id

Answer 2

您可以直接在where子句中添加它而不使用任何别名。

SELECT round（Sum（Zarada），2）AS Zarada， cms_cart_customers.Firstname，cms_cart_wallet.WalletType为WW， cms_cart_customers.Lastname，FROM_UNIXTIME（cms_cart_customers.d_ins，“％d。％m。％Y”）AS Datum_formatiran FROM（cms_cart_customers） LEFT JOIN cms_cart_wallet ON cms_cart_wallet.IdBuyer = cms_cart_customers.Id WHERE cms_cart_customers.IDReferral ='199'和cms_cart_wallet.WalletType = 7 GROUP BY cms_cart_customers.Id

Answer 3

您不需要if。简单的条件逻辑就足够了：

  WHERE cms_cart_customers.IDReferral = '199' AND
        (ww <> 7 or cms_cart_wallet.WalletType = 7)

处理NULL值：

  WHERE cms_cart_customers.IDReferral = '199' AND
        (COALESCE(ww, 0) <> 7 or cms_cart_wallet.WalletType = 7)

MySQL if-statment与where子句一起使用

3 个答案: