PHP and MySQL optional WHERE conditions - php

Question

I have the following problem: I want to let a user apply filters to a DB search.
I have three filters, A, B and C. All of them can be "empty", as in, the user doesn't care about them and selects "Any". Now I want to check this query against the DB records. I use a normal mysql query as in
$db_q = "Select * from table where row1 = '" . $A . "' and row2 = '" . $B . "' and row3 =
'" . $C . "'";
This works fine as long as the user enters anything specific for A,B,C (!= "any"). When "any" is selected, i get something like this: "Select * from table where row1 = "any/all" etc." I can't seem to figure out the correct syntax (if it's even possible) and I would like to avoid messy case distinction (if A == any, perform select; if B == empty.. and so on).
Any help is much appreciated.

Answer 1

The other answers are mostly correct, but this is a simpler way to accomplish what is needed:
$where = array();
if($A != 'any'){ // or whatever you need
$where[] = "A = $A'";
}
if($B != 'any'){ // or whatever you need
$where[] = "B = $B'";
}
if($C != 'any'){ // or whatever you need
$where[] = "C = $C'";
}
$where_string = implode(' AND ' , $where);
$query = "SELECT * FROM table";
if($where){
$query .= ' ' . $where_string;
}
This will allow for any combination of conditions and expansion.

Answer 2

Before your query you could use:
$tmp = "where ";
if($A and $A!="any" and $A!="not used")
$tmp .= "row1 = '".$A."'";
if($B and $B!="any" and $B!="not used")
$tmp .= "AND row2 = '".$B. "'";
if($C and $C!="any" and $C!="not used")
$tmp .= "AND row3 = '".$C."'";
$db_q = "Select * from table $tmp";

Answer 3

Try this:
$db_q = "Select * from table ";
if ($A != "any" || $B != "any" || $C != "any")
{
$db_q .= "where ";
}
$firstCondition = true;
if ($A != "any")
{
if (!$firstCondition)
$db_q .= "and ";
$db_q .= "row1 = '$A' ";
$firstCondition = false;
}
if ($B != "any")
{
if (!$firstCondition)
$db_q .= "and ";
$db_q .= "row2 = '$B' ";
$firstCondition = false;
}
if ($C != "any")
{
if (!$firstCondition)
$db_q .= "and ";
$db_q .= "row3 = '$C' ";
$firstCondition = false;
}

Answer 4

Try doing something like this:
if #param1 is not null
select * from table1 where col1 = #param1
else
select * from table1 where col2 = #param2
This can be rewritten:
select * from table1
where (#param1 is null or col1 = #param1)
and (#param2 is null or col2 = #param2)
Got the idea from Baron Schwartz's blog: https://www.xaprb.com/blog/2005/12/11/optional-parameters-in-the-where-clause/