Question

我想更新table1的所有字段，它们引用表2中的相等字段，并且它是：sum：示例：table1具有

 Fieldname  |   amount
 -------------------------
    a       |       200
    a       |       300 
    b       |       50
    b       |       150

现在我想将Fieldname相等的金额之和复制到table2的相关字段中，所以它在表2中看起来像

 Fieldname  |   SumAmount
 -------------------------
    a       |       500
    b       |       200

Answer 1

如果table2中已存在fieldNames，您可以执行以下操作：

UPDATE table2 t2
INNER JOIN
(SELECT fieldName, SUM(amount) as total
 FROM table1
 GROUP BY fieldName
) T1 ON t1.fieldName = t2.fieldName
SET t2.sumAmount = t1.total

否则，您必须INSERT：

INSERT INTO table2 (fieldName,sumAmount)
SELECT fieldName, SUM(amount)
FROM table1
GROUP BY fieldName

Answer 2

试试这个：

INSERT INTO table2(Fieldname, SumAmount)
SELECT Fieldname, SUM(amount) 
FROM table1 
GROUP BY Fieldname;

Answer 3

UPDATE table2 SET SumAmount= 
(SELECT SUM(amount) FROM table1 GROUP BY fieldname)x 
WHERE table2.fieldname=x.fieldname

Answer 4

UPDATE table1 t1
SET 
    t1.amount = t2.SumAmount
INNER JOIN table2 t2 ON t1.Fieldname = t2.Fieldname

使用重复字段的总和更新table1的列

4 个答案: