Concatenate 2 PHP variables into SQL statement

Question

I am developing a PHP system with Oracle and to "optimize" an update, I would need to concatenate a variable (with values from 1 to 3) in the name of the variable that I will pass in the instruction. The variables come from a form, and I need to pass one by one, without using array.

Below is a passage that is today:

$update .="CODIGO = '$produto_1' AND ";

The above example would need to pass something like this, where the $passo would have fixed values (today from 1 to 3):

$update .="CODIGO = '$produto_.$passo' AND ";

In that case I should pass as variable too $produto_1, afterward $produto_2......

Using the point to concatenate didn’t work. Any hints?

Answer 1

I used Extract to generate the variable test passo_X, but the applied logic would be for.

$arrayPassos = array(
    'passo_1' => 'teste1',
    'passo_2' => 'teste2',
    'passo_3' => 'teste3',
    'passo_4' => 'teste4',
);
extract($arrayPassos); // criada variaves passo_X

$out = '';
for ($i=1; $i <= count($arrayPassos); $i++){
    $out .= ${"passo_{$i}"};
}

Note

• in such cases it is best to use array, and not numbered variables.

Answer 2

This gets very complex, use arrays, for this reason they exist because if not you will have to use eval, which would be something like (recommend that don’t use eval, is only to exemplify):

$var1 = eval('return $produto_' . $passo);

$update .="CODIGO = '$var1' AND ";

Then do with array, which would be something like:

$produto = array();

$produto[1] = ...;
$produto[2] = ...;

$update .= "CODIGO = '" . $produto[$passo] . "' AND ";

You quoted form, so I can assume that refers to HTML, you can do so too:

<form method="POST" action="pagina.php">
    <input type="text" name="passo[]" value="a">
    <input type="text" name="passo[]" value="b">
    <input type="text" name="passo[]" value="c">
    <button>Enviar</button>
</form>

And in PHP you will get it like this:

<?php
print_r($_POST['passo']);

The exit will be:

Array
(
    [0] => a
    [1] => b
    [2] => c
)

Answer 3

Using the point to concatenate didn’t work. Any hints?

It did not work as expected because the attempt at concatenation is being made between quotation marks, the . is being interpreted as any character, and not as concatenation operator.

Follow another alternative:

$update .= "CODIGO = '{$produto}_{$passo}' AND ";

Editing: It is also possible reference the variable in a loop:

$produto_1 = "PROD1";
$produto_2 = "PROD2";
$produto_3 = "PROD3";

$limite = 3;
$update = "";

for ($passo = 1; $passo <= $limite; $passo++) {
    $update .= "CODIGO = '" . ${"produto_$passo"} . "' AND ";
}

echo $update;
// CODIGO = 'PROD1' AND CODIGO = 'PROD2' AND CODIGO = 'PROD3' AND

See DEMO

Answer 4

You can mount the concatenation with the function sprintf() also, the %s are exchanged for the relevant variables (values) in the order they appear.

$passo = $_POST['passo']; 
$update .= sprinf("CODIGO = '%s_%s'", $produto, $passo);