我有一个这样的表在MySQL:计数独特领域的MySQL
dancer1 | dancer2
------------------
jeff | Julia
john | Megan
jeff | Vanessa
我应该很容易,但我怎么算独特的舞者的数量(在这种情况下5)这个问题看起来像在这里questionned :MySQL Counting Distinct Values on Multiple Columns,但并不完全
我有一个这样的表在MySQL:计数独特领域的MySQL
dancer1 | dancer2
------------------
jeff | Julia
john | Megan
jeff | Vanessa
我应该很容易,但我怎么算独特的舞者的数量(在这种情况下5)这个问题看起来像在这里questionned :MySQL Counting Distinct Values on Multiple Columns,但并不完全
一个简单的联盟会给你一套所有的舞者:
select DISTINCT dancer1 as dancer from table
union
select DISTINCT dancer2 as dancer from table
如果你想计数:
select count(all_dancers.dancer) from (
select DISTINCT dancer1 as dancer from table
union
select DISTINCT dancer2 as dancer from table
) all_dancers
尝试此查询
select count(distinct dancer1,dancer2 ) from table
SELECT COUNT(DISTINCT dancer)
FROM
(SELECT dancer1 dancer
FROM my_table
UNION
SELECT dancer2
FROM my_table
) x;
您需要的数量为5此处给出..? –