Question

Suppose I have the table

      id      |       name       | number  |                address
--------------+------------------+---------+-------------------------------------
 1            | channel A        |      0  | http://stream01
 2            | channel B        |      2  | http://stream02
 3            | channel C        |      16 | http://stream03
 4            | channel B        |      2  | http://stream04
 5            | channel B        |      16 | http://stream05
 6            | channel C        |      16 | http://stream06
 7            | channel A        |      7  | http://stream07
 8            | channel A        |      5  | http://stream08
 9            | channel A        |      0  | http://stream09
...etc

I want to remove duplicate channels (rows with the same name and number). But I want the result to contain the other columns along with name and number.

The problem is which id and address I choose once I’ve removed the duplicates. I’m happy to choose the first it finds. So, for example, the result from the above table should be

      id      |       name       | number  |                address
--------------+------------------+---------+-------------------------------------
 1            | channel A        |      0  | http://stream01
 2            | channel B        |      2  | http://stream02
 3            | channel C        |      16 | http://stream03
 5            | channel B        |      16 | http://stream05
 7            | channel A        |      7  | http://stream07
 8            | channel A        |      5  | http://stream08
...etc

I realise I’ll probably need a SELECT name,number FROM table GROUP BY name,number in my query and the query should start off SELECT id,name,number,address FROM (..) but I just can’t think of a way to do this in one query.

Any ideas?

Answer 1

SELECT DISTINCT ON (name,number)
       id,
       name,
       number,
       address
  FROM table
 ORDER BY name,number,id;