Tagged Questions
0
votes
1answer
87 views
Error “column does not exist” in a SELECT with JOIN and GROUP BY querry
I'm using PostgreSQL 9.1 with a Ruby on Rails application.
I'm trying to list the last version of each "charge" (in my history table : hist_version_charges) belonging to the same project id ...
2
votes
1answer
762 views
Multiple “GROUP_CONCAT”s with WHERE clause
In a table as
id name type info
1 BMW car yes
2 Reno car no
3 IBM electronics no
4 Sony electronics yes
5 Mazda ...
2
votes
1answer
172 views
SELECT multiple sensor values in one query
Background
I have a couple of devices, each with a couple of sensors. I log these every now and then and stores them in a table described below. When someone requests a web page, I fetch a couple of ...
1
vote
2answers
400 views
GROUP BY two columns
I want to count two columns, but need to get the results of first column in one row.
SELECT country, COUNT(*)
FROM table1
GROUP BY country, type
This query gives me
country type COUNT(*)
...
