[英]MYSQL calculating an average on a count
I have a simple query that I want an average on. 我有一个简单的查询,希望获得平均值。 This is what it looks like now, and I want to know the average of my count per Opname_OpnameID.
这就是现在的样子,我想知道每个Opname_OpnameID的平均计数。
SELECT Opname_OpnameID, count(*) as 'behandelingen per opname'
FROM behandeling
GROUP BY Opname_OpnameID
If you want the average count, presumably over the entire table, then just do exactly that: 如果您想要平均计数(大概是整个表),则只需执行以下操作即可:
SELECT AVG(cnt) AS total_avg
FROM (
SELECT COUNT(*) AS cnt FROM behandeling GROUP BY Opname_OpnameID
) t;
You can use count(distinct)
and not use a subquery: 您可以使用
count(distinct)
而不使用子查询:
SELECT count(*) / count(distinct Opname_OpnameID)
FROM behandeling
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