SQL Query with multiple conditions WHERE [closed]

Your query is not a valid query, and therefore the mysqli_query is a BOOLEAN , in this case false .

You have other problems in the code. Dates or cycle here foreach ($v as $key => $value); , instead of adding in the query more conditions OR for each item in $pesquisa .

I think what you want is to have multiple possibilities for descricao and grau depending on what was searched, type algo para pesquisar would create 3 combinations, one for each word.

$pesquisa = $_POST["pesquisa"];
$v = explode(" ", $pesquisa);

$condicoes = []; // um array para guardar todas as condicoes
foreach ($v as $key => $value) {
    // adicionar ao array uma condicao por cada valor passado em $pesquisa
    $condicoes[] = "descricao LIKE '%{$value}%' OR grau LIKE '%{$value}%'";
}

$sql = "SELECT * FROM lentes WHERE " . implode(" OR ", $condicoes);

$resultado = mysqli_query($con, $sql);

// ... o resto do teu código

How it works

PHP eats arrays for breakfast, so be one of the most useful data structures in the language, especially when you are using a more procedural style of code, even when you use objects it will be useful, suggesting that you familiarize yourself with what you can read the PHP documentation on arrays .

The code I put in foreach is only adding items to the array, for example, imagine that $pesquisa is algo para pesquisar .

// aqui dividimos a string "algo para pesquisar" em cada espaço
$v = explode(" ", $pesquisa);

// isto cria um array assim
// Array
// (
//     [0] => algo
//     [1] => para
//     [2] => pesquisar
// )

// por cada palavra, adicionamos um item ao nosso array condicoes
$condicoes = []; 
foreach ($v as $key => $value) {
    $condicoes[] = "descricao LIKE '%{$value}%' OR grau LIKE '%{$value}%'";
}

// $condicoes, depois deste ciclo será
// Array
// (
//     [0] => descricao LIKE '%algo%' OR grau LIKE '%algo%'
//     [1] => descricao LIKE '%para%' OR grau LIKE '%para%'
//     [2] => descricao LIKE '%pesquisar%' OR grau LIKE '%pesquisar%'
// )

We can use the implode () , which is the opposite of explode (), to transform $ conditions in a string, and we can even (should!) check for $ conditions (that is, if something was added to the array.)

$sql_condicoes = ""; // o SQL das condições é vazio caso não existam condicoes
if (count($condicoes) > 0) {
    $sql_condicoes = " WHERE " . implode(" OR ", $condicoes);
}

$sql = "SELECT * FROM lentes" . $sql_condicoes;

mysqli_query returns an object on success and if it fails, returns a FALSE boolean, that is, most likely that $resultado is false and you are trying to fetch_array() boolean ( call a member function on boolean ).

What you can do to help debug this is to make one:

if (!$resultado) {
   // faz um tratamento de erro pra saber qual erro deu
   // e retorna algo para parar a execução deste script
}

And then you will only do $resultado->fetch_array() if $resultado is not FALSE .