How to select how many columns have the same value from mysql - php

Question

I have query that selects goes something like this:
$query = "SELECT members.*
FROM members
JOIN $nombre
ON members.member_ID=$nombre.friends";
$result = mysql_query($query) or die(mysql_error());
$number = mysql_num_rows($result);
$i = 0;
while($msg = mysql_fetch_assoc($result))
{
//store data in arrays
$peer_id[$i] = $msg['member_ID'];
$peer_state[$i] = $msg['home_state'];
$pro_political_views[$i] = $msg['political_views'];
$peer_district[$i] = $msg['district'];
$peer_first[$i] = $msg['first_name'];
$peer_last[$i] = $msg['last_name'];
$peer_issue[$i] = $msg['first_issue'];
$peer_second[$i] = $msg['second_issue'];
$peer_third[$i] = $msg['third_issue'];
$peer_stand[$i] = $msg['iStand'];
$peer_mail[$i] = $msg['email'];
$peer_pic[$i] = $msg['photo'];
++$i;
}
What this essentially does is get all the values from columns in the rows in the members from the members table where the member_ID is present in the $nombre table.
In the members table, there are two columns called "state" and "district". I want to make it so that php could tell me how many different values there are in the state and district columns for this query.
So, how could I go about writing a query or use php to tell how many how many peers are from a given state. I don't want to have to query the db once for each of the fifty states because that would take way too much time for the page to load. So, is there an efficient way to do this?
Thanks

Answer 1

...to tell how many how many peers are
from a given state
For states:
SELECT state, COUNT(m.member_ID) cnt
FROM members m
JOIN $nombre n ON m.member_ID=n.friends
GROUP BY state
and for districts:
SELECT 'district', COUNT(m.member_ID) cnt
FROM members m
JOIN $nombre n ON m.member_ID=n.friends
GROUP BY 'district'
This queries returns distinct values for states and districts and count of peers from them

Answer 2

You could use two queries, like so:
SELECT DISTINCT members.state
FROM members
JOIN $nombre
ON members.member_ID=$nombre.friends
and
SELECT DISTINCT members.district
FROM members
JOIN $nombre
ON members.member_ID=$nombre.friends
This will give you all of the unique states and districts back, which you can use or count or whatever.
Alternatively, add this somewhere in your while loop:
$all_states[$msg['state']] = 1;
$all_districts[$msg['district']] = 1;
Then, after the loop you can:
$state_count = count($all_states);
$district_count = count($all_districts);
The query approach would be faster by itself (assuming an index on the state and district columns), but the latter approach will be faster if you are already executing this loop anyway.
EDIT: To count unique districts in each state, replace
$all_districts[$msg['district']] = 1;
with something like
$all_districts[$msg['state'] . '--' . $msg['district']] = 1;
This will include the state in the array key too, and the count() call later will return all of the unique district-state combinations.

Answer 3

you can save the district in additional array like
$district[] = $msg['district'];
after the loop print_r using a function array_count_values
print_r(array_count_values($district));