SQL query empty field, select ALL option like * - php

Question

A php search page uses an SQL query to search for properties based on set criteria, in the example below the street "Harrison Road" is chosen:
search.php?city=1&rooms=3&rooms_upper=7&price_lower=55&price_upper=100&streetname=Harrison%20Road
I am looking for a way to leave the streetname blank and still SELECT ALL records as below:
search.php?city=1&rooms=3&rooms_upper=7&price_lower=55&price_upper=100&streetname=
I tried using the ' * ' symbol as with other SQL ocmmands to specify SELECT ALL but it does not work in this instance.
The problem is the search does not display any results while the street option is left blank.
The reason I am looking to run a search with an empty street criteria is because the search.php loads before the user selects a particular street using the drop down option on the page.
I would like it to SEARCH ALL records using the first criteria specified:
rooms, rooms_upper, price_lower, price_upper
The standard search page load has been left with the widest search criteria possible ( 3 < rooms < 7 ) and (£55 < rent < £75) in order to display ALL records before the user narrows the search criteria specifying a particular 'streetname' if desired.
Many Thanks!
Jeanclaude
The full SQL is here:
$sql=mysql_query("SELECT main_table.housenumber, main_table.housenumber, main_table.streetname,
max(main_table.rent) AS reviews_rent, main_table.rooms AS reviews_rooms,main_table.average,
houses.houseID, houses.path, houses.rooms AS houses_rooms,houses.rent AS houses_rent
FROM main_table
LEFT JOIN houses ON main_table.housenumber = houses.housenumber
AND main_table.streetname = houses.streetname
WHERE main_table.streetname='$page_streetname'
AND main_table.city=$city
AND main_table.verify='1'
AND main_table.rooms>='$rooms'
AND main_table.rooms<='$rooms_upper'
AND main_table.rent>=$price_lower
AND main_table.rent<=$price_upper
GROUP BY main_table.housenumber, main_table.streetname
ORDER BY average DESC, houseID DESC, reviewID DESC;");
I want to keep streetname in the WHERE clause, but I don't want to restrict the search if it is left blank.

Answer 1

How about creating the query dynamically.
Set up the base query without the streetname in the WHERE clause but include a sprintf string tag.
Then if $page_streetname has a value add the streetname selection to the query dynamically or if not just add nothing.
$q = "
SELECT main_table.housenumber,
main_table.streetname,
Max(main_table.rent) AS reviews_rent,
main_table.rooms AS reviews_rooms,
main_table.average,
houses.houseid,
houses.path,
houses.rooms AS houses_rooms,
houses.rent AS houses_rent
FROM main_table
LEFT JOIN houses
ON main_table.housenumber = houses.housenumber
AND main_table.streetname = houses.streetname
WHERE %s
main_table.city = $city
AND main_table.verify = '1'
AND main_table.rooms >= '$rooms'
AND main_table.rooms <= '$rooms_upper'
AND main_table.rent >=$ price_lower
AND main_table.rent <=$ price_upper
GROUP BY main_table.housenumber,
main_table.streetname
ORDER BY average DESC,
houseid DESC,
reviewid DESC";
$q = isset($page_streetname)
? sprintf( $q, "main_table.streetname = '$page_streetname' AND " )
: sprintf( $q, '');

Answer 2

That's easily solved with PHP (no need for sprintf()):
<?php
$page_streetname = empty($page_streetname)
? null
: "AND main_table.streetname = '{$page_streetname}'"
;
$result = mysql_query(
"SELECT
main_table.housenumber,
main_table.housenumber,
main_table.streetname,
max(main_table.rent) AS reviews_rent,
main_table.rooms AS reviews_rooms,
main_table.average,
houses.houseID,
houses.path,
houses.rooms AS houses_rooms,
houses.rent AS houses_rent
FROM main_table
LEFT JOIN houses
ON main_table.housenumber = houses.housenumber
AND main_table.streetname = houses.streetname
WHERE
main_table.city = '{$city}'
AND main_table.verify = 1
AND main_table.rooms >= '{$rooms}'
AND main_table.rooms <= '{$rooms_upper}'
AND main_table.rent >= {$price_lower}
AND main_table.rent <= {$price_upper}
{$page_streetname}
GROUP BY
main_table.housenumber,
main_table.streetname
ORDER BY
average DESC,
houseID DESC,
reviewID DESC"
);
?>