Hey all!
I'm using PostgreSQL 7.1 - question regarding subqueries.
Given a table defined thusly:
sample
=========
category integer not null,
value integer not null,
userid integer not null
Each user has multiple values given in multiple categories and there are many users.
I want an average of all values given in each category that belong to a particular user, as in
"select avg(value) from sample where category=(select distict category from sample where userid=5)"
where the output might be:
cat / value
=============
1 / 3
2 / 2.2
3 / 5.87
The above query doesn't work, I get:
ERROR: More than one tuple returned by a subselect used as an expression.
Any takers?
I'm using PostgreSQL 7.1 - question regarding subqueries.
Given a table defined thusly:
sample
=========
category integer not null,
value integer not null,
userid integer not null
Each user has multiple values given in multiple categories and there are many users.
I want an average of all values given in each category that belong to a particular user, as in
"select avg(value) from sample where category=(select distict category from sample where userid=5)"
where the output might be:
cat / value
=============
1 / 3
2 / 2.2
3 / 5.87
The above query doesn't work, I get:
ERROR: More than one tuple returned by a subselect used as an expression.
Any takers?