How do i create the array with the values being fetched from database in php

Question

Say i am having set of rows in a table and each row is having a column called city with some values assigned to it iam iterating through the result set and i need to assign the list of city values of each row in to an array only unique

     foreach($res as $row){
       $cities =array();
       $cities[] = $row['city'];
       //when i say 
       var_dump($cities);
       //Iam not able to get array .how do i do that 
       $maincities = array('A','B',C)
     }

chigley · Accepted Answer · 2010-10-04 18:26:53Z

3

You're resetting $cities to a new array for each row you loop through. Better would be:

$cities = array();
foreach ($res as $row)
{
    if ( ! in_array($row['city'], $cities)) {
        $cities[] = $row['city'];
    }
}

answered Oct 4, 2010 at 18:26

chigley

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3 Comments

Someone Over a year ago

iam getting null array when i try to compare the cities array with main city array if ( !in_array($row['city'], $mainarray)) { echo "one"; $cities[] = $row['city']; } var_dump($cities)

Wrikken Over a year ago

@some: Why do you use $mainarray when the answer states $cities? Sound more like mixing up variables (especially the NULL part...)

chigley Over a year ago

@Someone - you'll need to post up your full code if you want any more help. We're not here to guess! My answer will work when used correctly! What is $maincities compared to $cities?

Alin P. · Accepted Answer · 2010-10-04 18:27:40Z

2

You should but $cities =array();before the foreach loop. Now you are erasing the array at each iteration.

Regards, Alin

answered Oct 4, 2010 at 18:27

Alin P.

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Comments

Wrikken · Accepted Answer · 2010-10-04 18:28:10Z

2

You empty the $cities variable every time in the loop.
It is probably a lot better practise to only have unique cities in your resultset (SELECT DISTINCT city FROM ...)

answered Oct 4, 2010 at 18:28

Wrikken

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Comments

erenon · Accepted Answer · 2010-10-04 18:28:25Z

1

For example:

$cities =array();
foreach($res as $row){      
   $cities[] = $row['city'];       
}
var_dump($cities);

However it depends on the content of $res

answered Oct 4, 2010 at 18:28

erenon

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Comments

Matthew · Accepted Answer · 2010-10-04 18:30:36Z

1

Using keys to eliminate duplicates:

$cities = array();
foreach($res as $row)
  $cities[$row['city']] = true;
$cities = array_keys($cities);

answered Oct 4, 2010 at 18:30

Matthew

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1 Comment

Matthew Over a year ago

I agree. But some times you may need the non-distinct data as well, and you'd have to run a second query to get the distinct values. Example: If building a faceted search, you might want to display all of the results, along with a checkbox for each distinct city, category, etc, found within that resultset.

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