Question

I’m trying to create a webpage where the user can submit information that they know and select information they’d like returned. For example, if they know the ID number for their submission, they can enter it and ask for the returned values to be the ID number and product name.

The information that’s being retrieved is stored in a MySQL database, and the html page is laid out with a select menu, text boxes, and checkboxes (so that the user can select a name or enter other information, and then use the checkboxes to select the other information they want returned).

Here’s the relevant html:

<table><tr>
<form name="input" method="post" action="next.php">
<td width="120">Flowcell ID:<br />
<select name = "Flowcell_ID">
<option disabled="disabled" selected="selected">
Select...
</option>
<?php
$link = mysqli_connect("localhost","user","pass","db");
$query = "SELECT DISTINCT ID FROM table";
$result = mysqli_query($link, $query);
while ($row = mysqli_fetch_array($result)){
$id = $row['ID'];
echo "<option value=\"$id\">$id</option>";
}
mysqli_close($link);
?>
</select></td>
</tr><tr>
<td width="120">Name:<input type="text" name="Name" /></td>
</tr><tr>
<td width="120">Date:<input type="text" name="Date" /></td>
</tr><tr>
<td width="120">Group:<input type="text" name="Group" /></td>
</tr><tr>
<td width="120"><input type="checkbox" name="options[]" value="ID">ID</input></td>
<td width="120"><input type="checkbox" name="options[]" value="Name">Name</input></td>
<td width="120"><input type="checkbox" name="options[]" value="Date">Date</input></td>
<td width="120"><input type="checkbox" name="options[]" value="Group">Group</input></td>
</tr></table>

The only php I have so far is:

$id = $_POST['ID'];
$name = $_POST['Name'];
$date = $_POST['Date'];
$group = $_POST['Group'];

How would I produce a MySQL query that looks like

SELECT [checked checkboxes] FROM table WHERE [information field] = [user-entered information]

?

Thanks!

Answer 1

You can build the query incrementally:

$fields = array(
   'ID'   => 'id',
   'Name' => 'name',
   'Date' => 'date',
   'Group' => 'group',
);

$query = 'SELECT';  // Optional fields to be displayed may go here
$comma = ' ';       // and if they do, start with $comma = ', ';

$where = array();

foreach($fields as $post => $mysql)
{
    // here we have $post equal to 'ID', our POST field, and
    // $mysql equal to, say, 'Id' -- the MySQL field name.
    // Check whether options['ID'] is set. If so, we must get
    // the _POST[ID] field and check its contents against "Id" field in DB.
    if (in_array($post, $_POST['options']))
    {
        $query .= "$comma$mysql";
        $comma = ', ';
        // Add WHERE condition
        $where[] = "$mysql = '" . mysql_real_escape_string($_POST[$post]) . "'";
    }
}
// $comma, the separator between option fields, also doubles up as a check
// to see whether we have conditions.
// another possibility would be, "if (empty($where))"
if (' ' == $comma)
   die("You must select at least one checkbox!");

$query .= ' FROM table WHERE ';
// Build WHERE condition
$query .= '(' . implode(' AND ', $where).')';

// Other conditions may go here (e.g. " AND record_valid = 1 ")

$query .= ';';