if function inside sql query? - php

Question

function get_tags_by_criteria($gender_id, $country_id, $region_id, $city_id, $day_of_birth=NULL, $tag_id=NULL, $thread_id=NULL) {
$query = "SELECT tags.*
FROM tags, thread_tag_map, threads
WHERE thread_tag_map.thread_id = threads.id
AND thread_tag_map.tag_id = tags.id
AND threads.gender_id = $gender_id
AND threads.country_id = $country_id
AND threads.region_id = $region_id
AND threads.city_id = $city_id
AND tags.id LIKE '%$tag_id%'
AND threads.id LIKE '%$thread_id%'";
if(!$day_of_birth)
{
$query += "AND threads.min_day_of_birth <= '$day_of_birth AND threads.max_day_of_birth >= '$day_of_birth' ";
}
$query += "GROUP BY tags.name";
$result = $this->do_query($query);
return $result;
}
if no $day_of_birth is passed as an argument i want the sql to omit the 2 lines inside the if. i used:
$all_tags = $forum_model->get_tags_by_criteria(1, 1, 0, 0);
i wonder why this sql returns a error:
Couldn't execute query: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '0' at line 1

Answer 1

You're using the addition (+=) operator when you should be using the concatenation (.=) operator.
You should be escaping your inputs too, to avoid SQL injection - see mysql_real_escape_string()

Answer 2

there's missing white space between " and AND in appended string

Answer 3

Your problem is that you left out a ' by the date of birth.
Change it to AND threads.min_day_of_birth <= '$day_of_birth' (Note closing ' and opening )
Also, as others have pointed out, you should write $query .= instead of $query +=
(note .)
You have a SQL Injection vulnerability; you should use parameters.
Remember Bobby Tables!

Answer 4

.= is used for string concatenation in PHP, not +=

Answer 5

You can also use placeholders in your query. If an option/parameter is set the script sets the contents of the placeholder to the appropriate sql code otherwise the placeholder is empty/null.
e.g.
function get_tags_by_criteria($gender_id, $country_id, $region_id, $city_id, $day_of_birth=NULL, $tag_id=NULL, $thread_id=NULL) {
if ( !is_null($day_of_birth) ) {
$day_of_birth = "AND ('$day_of_birth' BETWEEN threads.min_day_of_birth AND threads.max_day_of_birth)"
}
$query = "
SELECT
tags.*
FROM
tags, thread_tag_map, threads
WHERE
thread_tag_map.thread_id = threads.id
AND thread_tag_map.tag_id = tags.id
AND threads.gender_id = $gender_id
AND threads.country_id = $country_id
AND threads.region_id = $region_id
AND threads.city_id = $city_id
AND tags.id LIKE '%$tag_id%'
AND threads.id LIKE '%$thread_id%'
{$day_of_birth}
GROUP BY
tags.name
";
$result = $this->do_query($query);
return $result;
}
edit: as mentioned before: keep the possible sql injection in mind.