… where count(col) > 1

问题:

I have a table like this:

+-----+-----+-------+
| id  | fk  | value |
+-----+-----+-------+
| 0   | 1   | peter |
| 1   | 1   | josh  |
| 3   | 2   | marc  |
| ... | ... | ...   |

I'd like now to get all entries which have more than one value. The expected result would be:

+-----+-------+
| fk  | count |
+-----+-------+
| 1   | 2     |
| ... | ...   |

I tried to achieve that like this:

select fk, count(value) from table where count(value) > 1;

But Oracle didn't like it.

So I tried this...

select * from (
    select fk, count(value) as cnt from table
) where cnt > 1;

...with no success.

Any ideas?

回答1:

Use the having clause for comparing aggregates.

Also, you need to group by what you're aggregating against for the query to work correctly. The following is a start, but since you're missing a group by clause still it won't quite work. What exactly are you trying to count?

select fk, count(value) 
from table 
group by fk
having count(value) > 1;