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Return first element in array_agg()

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I am writing a query to get all players for all teams. Instead of looping in the application, I decided to get the players of all teams in a single query using array_agg(). I have written the query as follows:

SELECT team_id, array_agg(team_name) AS teamname,        array_agg(player_id||'##'||player_name) AS playerdetails FROM team INNER JOIN players ON team_id = player_team GROUP BY team_id 

This query gives me the result as below, in the result set the teamname is being repeated (exactly to the no. of players)

team_id             team_name                                                                   playerdetails 1       {Australia,Australia,Australia,Australia}                       {"5##Glenn Donald McGrath","6##Shane Warne","2##Steve Waugh","1##Adam Gilchrist"} 2       {India,India,India,India}                                       {"8##Kapil Dev","11##Saurav Ganguly","3##Rahul Dravid","9##Sachin Tendulkar"} 3       {"South Africa","South Africa","South Africa","South Africa"}   {"12##Gary Kristen","4##Shaun Pollock","7##Jacques Kallis","10##Alan Donald"} 

Is there any way to return the result like this

team_id             team_name                                                                   playerdetails 1                   Australia                       {"5##Glenn Donald McGrath","6##Shane Warne","2##Steve Waugh","1##Adam Gilchrist"} 

I have achieved it using a subquery, but want to know if its possible to write it without the subquery

SELECT team_id, teamname[1], playerdetails FROM (   SELECT team_id, array_agg(team_name) AS teamname,          array_agg(player_id||'##'||player_name) AS playerdetails   FROM team   INNER JOIN players ON team_id = player_team   GROUP BY team_id) AS tempresult   

The sqfiddle is here. And I am using Postgresql 8.4

[EDIT]
I was actually thinking of hack to the GROUP BY limitation column "team.team_status" must appear in the GROUP BY clause or be used in an aggregate function when try to retrieve the a column which was not been specified in group by

SELECT team_id, array_agg(team_name) AS teamname,        array_agg(player_id||'##'||player_name) AS playerdetails,        team_status -- could be replaced by something like array_agg(team_status)[0] or customfunction(team_status) FROM team INNER JOIN players ON team_id = player_team GROUP BY team_id    
like image 216
Nandakumar V Avatar asked Jun 23 '15 08:06

Nandakumar V


1 Answers

It was actually a mistake from my part... the answer to my first question lies in that query itself. I just have to enclose the (array_agg(team_name))[1], earlier I tried it without the brackets.

SELECT team_id, (array_agg(team_name))[1] AS teamname,      array_agg(player_id||'##'||player_name) AS playerdetails FROM team INNER JOIN players ON team_id = player_team GROUP BY team_id 
like image 53
Nandakumar V Avatar answered Sep 27 '22 16:09

Nandakumar V