Example solution for a question posted in a PHP Facebook group

example_query.php

<?php
/*
The question:

if ( $date_text == 'Sunday' ){
    $sql = "update table set sun = $date where "id ='$_REQUEST[num]";
    $sql1= "update table set sun = $date where "id ='$_REQUEST[num1]";
    mysql_query($con,$sql);
    mysql_query($con,$sql1);
}

I have more than 7 SQL queries... $sql1, $sql2, etc
How can i make all these lines short and easy to read?
*/

$pdo = new PDO('some valid DSN');
$date_text = $_REQUEST['some-field'];
$date = $_REQUEST['some-other-field'];

//define the valid weekday columns associated with the date field
$dateColumns = [
    'Sunday'    => 'sun',
    'Monday'    => 'mon',
    'Tuesday'   => 'tues',
    'Wednesday' => 'wed',
    'Thursday'  => 'thurs',
    'Friday'    => 'fri',
    'Saturday'  => 'sat'
];

if (!array_key_exists($date_text, $dateColumns)) {
  //handle the error
}

//Retrieves all the IDs that are being updated
$queryParams = [$date];
for($i = 1; $i < 10; $i++) {
    $idKey = 'num' . $i;
    if ($_REQUEST[$idKey]) {
        $queryParams[] = $_REQUEST[$idKey];
    } 
}

//Create the SQL "in" clause string using placeholders
$idClause = trim( str_repeat('?, ', count($ids)), ', ');

//Create and then execute the SQl query
$sqlClause = <<<SQL
UPDATE `table` SET {$dateColumns[$date_text]} = ? WHERE id IN($idClause)
SQL;

$query = $pdo->prepare($sqlClause);
$query->execute($queryParams);