foreach loop with sql query in foreach loop

Question

I need help with this loop... I have table with address data:

konto_odbiorcy   nazwa     miasto     zip_code    ulica
6                 firm 1    Warsaw     02-174      street 1
23                firm 2    Krakow     05-400      street 2
435               firm 3    Warsaw      26-143      street 3
534               firm 4    Kielce     14-171      street 4
643               firm 5    Krakow     08-199      street 5
...something about 5000 entries

and mysql query:

$sql = 'SELECT
    konto_odbiorcy,nazwa,miasto,zip_code,ulica
FROM
    klienci_ax_all
WHERE
    sales_group IN ("IN","KD","TK","SG","TD")
ORDER BY
    miasto
ASC';

$res = mysql_query ($sql, $link ) or die ('request "Could not execute SQL query" '.$sql);

$cities = array();

while ($row = mysql_fetch_array($res)){
    $cities[$row['miasto']][] = $row;
}

foreach ($cities as $miasto => $_cities){
    echo $miasto;

    foreach ($_cities as $data){
        $sql1 = "SELECT date 
                 FROM 3ce_event
                 WHERE number=".$data['konto_odbiorcy']."
                 AND date <= CURDATE())
                 ORDER BY date
                 DESC LIMIT 0,1";
        $sql_result1 = mysql_query ($sql1, $link ) or die ('request "Could not execute SQL query" '.$sql1);

        $sql2 = "SELECT date FROM 3ce_event
                 WHERE number=".$data['konto_odbiorcy']."
                 AND date >= CURDATE()) ORDER BY date ASC LIMIT 0,1";
        $sql_result2 = mysql_query ($sql2, $link ) or die ('request "Could not execute SQL query" '.$sql2);


        while ($row1 = mysql_fetch_assoc($sql_result1)) {
            if($row1["date"] <> $obecna_data) {
                $data_ostatniej_wizyty = $row1["date"];
              }
        }

        while ($row2 = mysql_fetch_assoc($sql_result2)) {
            if( $row2["date"] == $obecna_data) {
                $data_nastepnej_wizyty = 'dzis';
            } else {
                $data_nastepnej_wizyty = $row2["date"];
            }
        }
    }
}

result:

Kielce
    - firm 4
Krakow
    - firm 2
    - firm 5
Warsaw
    - firm 1
    - firm 3

now it works but awesome slow, when first i search whole table and search first "city", then search again for company ("nazwa")that is located in the particular city.

my question is how to improve this to work faster?

EDIT

I pasted my second mysql query into second foreach loop.

Answer 1

First, check to see if your table has indexes, mainly on "sales_group" and "miasto" fields, because you use them to filter and order. If you apply other filters, make sure the table has indexes on them.

If "sales_group" is char or varchar, consider making it a foreign key or a ENUM field.

Last (and harder) suggestion: consider using pagination. That way, instead of dumping the whole table to the screen, you would be showing, for example, 20 records at a time.

Answer 2

Don't do those SQL queries in the loop. Combine them in one SQL statement:

$sql = 'SELECT a.konto_odbiorcy, a.nazwa, a.miasto, a.zip_code, a.ulica
, max(e1.date) as date_le_curdate
, min(e2.date) as date_ge_curdate
FROM klienci_ax_all as a
LEFT JOIN 3ce_event as e1 ON (a.konto_odbiorcy=e1.number AND e1.date <= CURDATE())
LEFT JOIN 3ce_event as e2 ON (a.konto_odbiorcy=e2.number AND e2.date >= CURDATE())
WHERE a.sales_group IN ("IN","KD","TK","SG","TD")
GROUP BY a.konto_odbiorcy
ORDER BY a.miasto ASC';

The table konto_odbiorcy should have an index on sales_group - maybe combined with miasto (assuming that konto_odbiorcy is the primary key or at least a unique key). 3ce_event should have an index on number. But fine tuning depends on which data your tables contain.