How to mount a query with optional conditions?

Question

In the example:

SELECT * FROM exemplo WHERE ID in(2, 3, 4) 

He brings if he has these ID at the bank.

How to mount a query which places this condition only if the array in PHP have elements?

PHP:

$id= implode(', ', $_GET['id']);
$nome= implode(', ', $_GET['nome']);
$cidade= implode(', ', $_GET['cidade']);

$query = mysql_query("SELECT * FROM EXEMPLO WHERE id IN($id) AND nome IN($nome) AND cidade IN($cidade)");

//Se tiver de acordo com a condição traz a linha dentro da condição, se não traz todas as linhas.

I tried it like this, but I don’t know if it’s right;

$id= "(id='".implode("' OR id='", $_GET['id'])."') AND";
$nome= "(nome='".implode("' OR nome='", $_GET['nome'])."') AND";
$cidade= "(cidade='".implode("' OR cidade='", $_GET['cidade'])."')";

$query = mysql_query("SELECT * FROM EXEMPLO WHERE $id $nome $cidade");

Answer 1

Better resolve in PHP and analyze if the array is empty or not. If it is empty, bring everything, if it is not, use the condition. After the various changes in formulation, according to the comments I would do something like this:

$query = "SELECT * FROM exemplo WHERE TRUE";
if (!empty($condicao1)) {
    $lista = implode(",", $condicao1);
    $query .= " AND ID NOT IN ($lista)";
}
if (!empty($condicao2)) {
    $lista = implode(",", $condicao2);
    $query .= " AND NOME NOT IN ($lista)";
}
if (!empty($condicao3)) {
    $lista = implode(",", $condicao3);
    $query .= " AND CIDADE NOT IN ($lista)";
}

I put in the Github for future reference.

Placed echo Just to illustrate, use in the PDO as you see fit. Of course if I had the code, I knew the real situation, I could help more, but abstractly this is it. In concrete situation I would sophisticate this.

This technique can be used to mount any type of condition.