[英]MySQL Join two tables displaying '0' in one column based on another column's value
[英]MySQL query to sum one column and count another column, from two tables, based on a common value?
我在嘗試構建一個查詢時遇到問題。 我希望在這里能得到一點幫助......
我有兩張桌子。 每個表有兩列。 它們描述如下:
表:“令牌”
Column 1: "Name" varchar(20)
Column 2: "Color" varchar(10)
表:“分數”
Column 1: "Name" varchar(20)
Column 2: "Points" Int
我想要一個查詢,該查詢將列出每個名稱一次,並為每個名稱列出該名稱的點總和,以及 Color="RED" 的計數
表 1 的樣本數據:
"BOB","GREEN"
"LARRY","RED"
"JIM","BLUE"
"JIM","RED"
"FRANK","RED"
"BOB","BLUE"
"JIM","RED"
表 2 的樣本數據:
"LARRY",100
"BOB",40
"JIM",200
"BOB",100
"PAUL",250
我的表 output 將類似於(行順序不重要):
BOB,140,0
LARRY,100,1
JIM,200,2
FRANK,0,1
PAUL,250,0
我怎樣才能做到這一點?
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
如果任一表中缺少name
,則可以使用union all
代替:
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
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