Question

我有一张这样的桌子：

uploadFiles(): void {
 const dialogRef = this.dialog.open(AddNewFilesOrImagesComponent, {
   panelClass: 'myClass',
 });
}

我想用sum（columnC）查找不同的columnA和columnB 该表是ORDER BY SUM（columnC）DESC。

.myClass {
  max-height: 95%;
  width: 620px;
  overflow-y: auto;
{

当我尝试

importer     exporter     quantity    
A            D           0.9
A            B           0.9
A            B           0.1
B            E           9.4
B            E           8.9
B            D           9.4
C            P           9.0
C            V           1.0
C            P           0.9

MYsql显示的表不是columnA和columnB不同，实际上，它显示了重复的columnA和columnB，并且没有将columnC加起来。

Answer 1

尝试一下：

SELECT   importer,
         exporter,
         SUM(quantity) AS sum_quantity
FROM     tablename
GROUP BY importer,
         exporter
ORDER BY sum_quantity DESC;

Answer 2

尝试如下

 SELECT 
 IMPORTER, EXPORTER, sum(QUANTITY)
 FROM Tablename group by IMPORTER, EXPORTER

Answer 3

@GordonLinoff暗示，您需要的是GROUP BY查询

SELECT 
    IMPORTER, 
    EXPORTER, 
    SUM(QUANTITY)
FROM Tablename
GROUP BY
    IMPORTER, 
    EXPORTER
ORDER BY 
    SUM(QUANTITY) DESC;

Answer 4

这是基本的GROUP BY：

 SELECT 
 IMPORTER, EXPORTER, SUM(QUANTITY) AS SUMQUANTITY
 FROM Tablename
 GROUP BY IMPORTER, EXPORTER
 ORDER BY SUMQUANTITY DESC;

用sum（cloumnC）选择不同的columnA和columnB

4 个答案: