求和多行SQL

Question

这是我的代码：

SELECT Invoice_detail.Xtype, 
       Invoice_detail.Totallineprice
FROM Invoice_detail Invoice_detail
      INNER JOIN Invoice_head Invoice_head ON 
     (Invoice_head.idx = Invoice_detail.Xinvoicehead)
WHERE ( Invoice_detail.Totallineprice <> 0 )
       AND ( Invoice_head.xCurrency = 1 )
ORDER BY Invoice_detail.Xtype

返回：

301  -  50
291  -  56.25
291  -  75
70   -  (125)
70   -  50
70   -  75

如何将此代码汇总，以便我的结果看起来更像这样？

301  -  50
291  -  131.25
70   -  0

感谢您的帮助！

Answer 1

尝试此查询，使用Sum为使用GROUP BY的第一列组（Invoice_detail.Xtype）总结第二列（Invoice_detail.Totallineprice）

SELECT Invoice_detail.Xtype, 
       SUM(Invoice_detail.Totallineprice)
FROM Invoice_detail Invoice_detail
      INNER JOIN Invoice_head Invoice_head ON 
     (Invoice_head.idx = Invoice_detail.Xinvoicehead)
WHERE ( Invoice_detail.Totallineprice <> 0 )
       AND ( Invoice_head.xCurrency = 1 )
GROUP BY  Invoice_detail.Xtype
ORDER BY Invoice_detail.Xtype