我认为这就是您要寻找的。NEW_BAL是QTY从余额中减去的s 的总和：
SELECT master_table.ORDERNO,
master_table.ITEM,
SUM(master_table.QTY),
stock_bal.BAL_QTY,
(stock_bal.BAL_QTY - SUM(master_table.QTY)) AS NEW_BAL
FROM master_table INNER JOIN
stock_bal ON master_bal.ITEM = stock_bal.ITEM
GROUP BY master_table.ORDERNO,
master_table.ITEM
如果要使用新余额更新项目余额，请使用以下命令：
UPDATE stock_bal
SET BAL_QTY = BAL_QTY - (SELECT SUM(QTY)
FROM master_table
GROUP BY master_table.ORDERNO,
master_table.ITEM)
假设您向后发布减法；它从天平中按顺序减去数量，这在不了解表格的情况下最有意义。如果我错了，只需交换这两个即可更改它：
(SUM(master_table.QTY) - stock_bal.BAL_QTY) AS NEW_BAL
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