Question

我在尝试建立的查询时遇到问题。我希望在这里有所帮助...

我有两个桌子。每个表都有两列。它们的描述如下：

表：“令牌”

 Column 1: "Name" varchar(20)
 Column 2: "Color" varchar(10)

表格：“得分”

 Column 1: "Name" varchar(20)
 Column 2: "Points" Int

我想要一个查询，该查询将列出每个名称一次，并且每个名称的总点数以及该位置的颜色=“ RED”

表1的样本数据

"BOB","GREEN"
"LARRY","RED"
"JIM","BLUE"
"JIM","RED"
"FRANK","RED"
"BOB","BLUE"
"JIM","RED"

表2的样本数据

"LARRY",100
"BOB",40
"JIM",200
"BOB",100
"PAUL",250

我的表格输出类似于（行顺序并不重要）：

BOB,140,0
LARRY,100,1
JIM,200,2
FRANK,0,1
PAUL,250,0

我该怎么做？

Answer 1

您可以聚合，然后加入：

select t1.name, t1.reds, t2.points
from (select name, sum(color = 'RED') reds from table1 group by name) t1
inner join (select name, sum(points) points from table2 group by name) t2 
    on t1.name = t2.name

如果两个表中均缺少name，则可以改用union all：

select name, sum(reds) reds, sum(points) points
from 
    select name, 1 reds, 0 points from table1 where color = 'RED'
    union all
    select name, 0, points points from table2
) t 
group by name

MySQL查询基于一个公共值从两个表中求和一列并计算另一列？

1 个答案: