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Re: Fast/Easy way to extract a column from multi-dimensional array?

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Jeff North wrote:

> John Drako wrote:
>>| I'm looking for a way to get all the values from the column of a two
>>| dimensional array.
>>| 
>>| For example, I have a query on a mysql database that returns 10 rows
>>| from the database, I would like to quickly (read low cpu load) extract
>>| all the IDs from all the rows returned to reuse in another query.
>>| 
>>| So let's say I use:
>>| 
>>| $arr = mysqli_fetch_all($result, MYSQLI_ASSOC);
>>| 
>>| and $arr looks like:
>>| 
>>| RecordID, name, last name, title
>>| RecordID, name, last name, title
>>| RecordID, name, last name, title
>>| RecordID, name, last name, title
>>| RecordID, name, last name, title
>>| RecordID, name, last name, title
>>| etc...
>>| 
>>| I need to get all the 'RecordID' from the results to reuse in other
>>| queries.
>>| 
>>| Is there a built in PHP function (compiled code) to accomplish this?
>>| I've read the definitions of all the functions related to arrays and if
>>| it exists, I didn't find it.
>>| 
>>| The site is very busy and CPU cycles count. I'm trying to avoid left
>>| joining three gigantic tables.
> 
> Let the database do it for you - look at group_concat().

GROUP_CONCAT() could only return a string of the concatenated non-NULL 
RecordIDs.  That is probably not what the OP is looking for ("reuse in
other queries").

<http://dev.mysql.com/doc/refman/5.1/en/group-by-functions.html>

I fail to see how you could suggest such error-prone and expensive an 
approach (first concatenation in MySQL, then splitting in PHP) when *the* 
solution has been presented already.

Please skip the attribution novel next time.


PointedEars
-- 
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a Web page appears to be yearning for the bad old days, before the Web,
when you had very little chance of reading a document written on another
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Thread

Fast/Easy way to extract a column from multi-dimensional array? John Drako <jbravo556@gmail.removethis.com> - 2012-01-27 15:08 -0500
  Re: Fast/Easy way to extract a column from multi-dimensional array? "J.O. Aho" <user@example.net> - 2012-01-27 21:50 +0100
    Re: Fast/Easy way to extract a column from multi-dimensional array? "M. Strobel" <sorry_no_mail_here@nowhere.dee> - 2012-01-27 22:49 +0100
  Re: Fast/Easy way to extract a column from multi-dimensional array? Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2012-01-27 21:52 +0100
    Re: Fast/Easy way to extract a column from multi-dimensional array? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-01-27 22:42 +0100
      Re: Fast/Easy way to extract a column from multi-dimensional array? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-01-27 22:55 +0100
      Re: Fast/Easy way to extract a column from multi-dimensional array? Thomas Mlynarczyk <thomas@mlynarczyk-webdesign.de> - 2012-01-27 23:49 +0100
  Re: Fast/Easy way to extract a column from multi-dimensional array? Jeff North <jnorthau@yahoo.com.au> - 2012-01-28 13:52 +1100
    Re: Fast/Easy way to extract a column from multi-dimensional array? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-01-28 21:28 +0100
  Re: Fast/Easy way to extract a column from multi-dimensional array? Arno Welzel <usenet@arnowelzel.de> - 2012-01-28 09:49 +0100
    Re: Fast/Easy way to extract a column from multi-dimensional array? John Drako <jbravo556@gmail.removethis.com> - 2012-01-29 13:54 -0500

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