I wish to find out the count of distinct rows in a MySQL DB.
我希望找到MySQL DB中不同行的计数。
id | val1 | val2 | val3
1 | 1 | 1 | 1
2 | 1 | 1 | 1
3 | 2 | 2 | 2
4 | 2 | 2 | 2
On the table above the query would return
在上面的表中，查询将返回
val1 | val2 | val3 | count
1 | 1 | 1 | 2
2 | 2 | 2 | 2
Does anyone know a reasonably efficient way of achieving this in MySQL.
有人知道在MySQL中实现这一目标的一种合理有效的方法吗?
1 个解决方案
#1
5
You need to use GROUP BY clause for this:
您需要使用GROUP BY子句:
SELECT val1, val2, val3, count(*) AS count
FROM mytable GROUP BY val1, val2, val3
See this fiddle
#1
5
You need to use GROUP BY clause for this:
您需要使用GROUP BY子句:
SELECT val1, val2, val3, count(*) AS count
FROM mytable GROUP BY val1, val2, val3