creating a sql query with php - php

Question

i am having this problem and I am trying to come up with the best and most efficient solution. I have a php website with 19 different inputs, all of them are optional and I am using the get method. With those inputs, i have to find the information that matches the data base and return it. The problem I am having is creating the query that will work.
$query = "SELECT * FROM TEST.table";
if(($_GET['Transmission_Line_Designation'] ==="") && ($_GET['Switch_Number'] === "") && ($_GET['Telecom_Circuit_Number'] === "")
&& ($_GET['Transmitter_Frequency'] === "") && ($_GET['Receiver_Frequency'] === "") && ($_GET['power_level'] === "")
&& ($_GET['Phase'] === "") && ($_GET['Modulate'] === "") && ($_GET['trap_type'] === "") && ($_GET['line_tuner_type'] === ""))
//checks if there were no input, if there werent any, display all columns and rows from the data base
{
}
else
{
This is where i'm having the problem, if the users inputs the first input, it will work , however, if the user leaves the first input blank, the query that comes out is "where and" something something, I was thinking about using a lot of if loops to check conditions and add a flag but I am pretty sure there is an easier way to do it.
$query.= " where ";
if
$query .= ($_GET['Transmission_Line_Designation'] === "") ? '' : 'Line_Designation = "'.$_GET['Transmission_Line_Designation'].'"';
$query .= ($_GET['Switch_Number'] === "") ? '' : ' and Switch_Number = "'.$_GET['Switch_Number'].'"';
$query .= ($_GET['Telecom_Circuit_Number'] === "") ? '' : ' and Telecom_Circuit_Number = "'.$_GET['Telecom_Circuit_Number'].'"';
$query .= ($_GET['Transmitter_Frequency'] === "") ? '' : ' and Transmitter_Frequency = "'.$_GET['Transmitter_Frequency'].'"';
$query .= ($_GET['Receiver_Frequency'] === "") ? '' : ' and Receiver_Frequency = "'.$_GET['Receiver_Frequency'].'"';
$query .= ($_GET['power_level'] === "") ? '' : ' and power = "'.$_GET['power_level'].'"';
$query .= ($_GET['Voltage'] === "") ? '' : ' and voltage = "'.$_GET['Voltage'].'"';
$query .= ($_GET['Phase'] === "") ? '' : ' and Phase= "'.$_GET['Phase'].'"';
$query .= ($_GET['Modulate'] === "") ? '' : ' and Modulate = "'.$_GET['Modulate'].'"';
$query .= ($_GET['trap_type'] === "") ? '' : ' and trap = "'.$_GET['trap_type'].'"';
$query .= ($_GET['line_tuner_type'] === "") ? '' : 'and ltunner = "'.$_GET['line_tuner_type'].'"';
echo $query;
}
Thank you guys for your help in advance, i appreciate it.

Answer 1

Throw in a dummy boolean expression first, so that all of your other criteria can start with "AND". Like this:
$query.= " where 1=1 ";
if
$query .= ($_GET['Transmission_Line_Designation'] === "") ? '' : 'AND Line_Designation = "'.$_GET['Transmission_Line_Designation'].'"';
$query .= ($_GET['Switch_Number'] === "") ? '' : ' and Switch_Number = "'.$_GET['Switch_Number'].'"';
$query .= ($_GET['Telecom_Circuit_Number'] === "") ? '' : ' and Telecom_Circuit_Number = "'.$_GET['Telecom_Circuit_Number'].'"';
$query .= ($_GET['Transmitter_Frequency'] === "") ? '' : ' and Transmitter_Frequency = "'.$_GET['Transmitter_Frequency'].'"';
$query .= ($_GET['Receiver_Frequency'] === "") ? '' : ' and Receiver_Frequency = "'.$_GET['Receiver_Frequency'].'"';
$query .= ($_GET['power_level'] === "") ? '' : ' and power = "'.$_GET['power_level'].'"';
$query .= ($_GET['Voltage'] === "") ? '' : ' and voltage = "'.$_GET['Voltage'].'"';
$query .= ($_GET['Phase'] === "") ? '' : ' and Phase= "'.$_GET['Phase'].'"';
$query .= ($_GET['Modulate'] === "") ? '' : ' and Modulate = "'.$_GET['Modulate'].'"';
$query .= ($_GET['trap_type'] === "") ? '' : ' and trap = "'.$_GET['trap_type'].'"';
$query .= ($_GET['line_tuner_type'] === "") ? '' : 'and ltunner = "'.$_GET['line_tuner_type'].'"';
echo $query;
}

Answer 2

What's the problem use if? And loop?
100% sure it will better to maintaince than this code....
try:
foreach($_GET as $key=>$value){
if($value !== '')
switch($key){
case "Modulate":
dosomething();
break;
}
}
It'll much better to maintaince.

Answer 3

Try the below, added some checking too.
<?php
$sql = "SELECT * FROM table WHERE ";
$count = count($_GET);
if ($count) { // check if $_GET has any values at all
foreach ($_GET as $key => $value) {
if ($value) { // check if $value not empty
$sql .= $key . " = " . "'" . $value . "', ";
}
}
$sql = rtrim($sql, ", ");
}
echo $sql;
?>