Create update query for dynamic database - php

Question

I am trying to update a row in a mysql database. To do this, I would use a simple query like this:
"UPDATE `contactinfo` SET `Company` = 'Google', WHERE `id` = '1';"
The problem is that the database is dynamic and users can add columns at any time. So I do not know the names of the columns. To find the names and create a form to post to the page that will actually do the mysql work uses this code:
<?php
$result = mysql_query("select * from contactinfo WHERE `id` = '".$rid."';");
if (!$result) {
die('Query failed: ' . mysql_error());
}
$i = 0;
while ($i < mysql_num_fields($result)) {
$meta = mysql_fetch_field($result, $i);
if (!$meta) {
echo "ERROR";
}
$name = $meta->name;
$r = mysql_fetch_array(mysql_query("select * from contactinfo WHERE `id` = '".$rid."';"));
$content = $r[$name];
if($name != 'id') {
echo "<tr><td align='center'><div align='left'>Edit ".$name."</div></td></tr>";
echo "<tr><td align='center'><input type='text' value='" . $content . "' /></td></tr>";
}
$i++;
}
mysql_free_result($result);
?>
This creates a nice little table with input boxes that allow the user to edit the content of the row that has been selected. The row id number($rid) is used to identify which row needs to be changed.
My question is, how can I get the new content for the row from the posted form and create a query to update it? I can't seem to figure out how to dynamically get the names of the form as well as the new content to the write the query.
If any clarification is needed just let me know and all help is appreciated.
Thanks.

Answer 1

The easiest way is to name the fields in the form exactly how the name of the fields in the database are.
Lets say you have this form
<form action="">
<input name="field[firstname]">
<input name="field[lastname]">
<input name="field[address]">
</form>
You should probably be able to create the form based on the fields names too, you are probably already doing this.
In the file that processes the response you can do something like this:
foreach($_POST['field'] as $field_name => $field_value) {
$sql_str[] = "{$field_name} = '{$field_value}'";
}
This just goes through the 'field' array that comes from post and puts the proper update text into another array.
Then just do a
mysql_query("UPDATE contactinfo SET ".implode(',', $sql_str)." WHERE `id` = '".$rid."';")
To put it into the database.

Answer 2

What you can do is add a column in the database with a bit flag and if the user is new or old, the flag will reflect it.
that way you can update the user to say if it is new or old.
hope this helps.

Answer 3

You might do well to investigate whether there is an ORM framework that you could use.
Anyway, the simplest way to do what you want is to pass the name of the field in the INPUT field.
$content = AddSlashes($content); // You may need HTMLEntities() here
$field = <<<FIELD
<input type="text" value="$content" />
FIELD;
Also, another useful trick to employ is to either supply an array of "protected" fields, or specify a prefix that makes the field unchangeable. For example, you almost certainly do not want a user to be able to change the primary keys.
So you could generate the form with
if ('id' == $meta->name or 'pk' == $meta->name or (0 === strpos($meta->name, 'pk_')))
{
// This is a primary key field
$html .= <<<PKFIELD
<input type="hidden" name="{$meta->name}" value="{$contents}" />
PKFIELD;
continue;
}
if (0 === strpos($meta->name, 'hf_'))
{
// hidden field, ignored (can't be changed)
continue;
}
if (0 === strpos($meta->name, 'ro_'))
{
// read-only field, shown but without even the name
$html .= <<<ROFIELD
<input type="text" readonly="readonly" class="readonly" value="{$contents}" />
ROFIELD;
continue;
}
Or you could use a fixed-size prefix and an array of templates:
$fieldtpls = array(
'pk_' => '<input type="hidden" name="{NAME}" value="{VALUE}" />',
'ta_' => '<textarea name="{NAME}">{VALUE}</textarea>',
'ro_' => '<input type="text" value="{VALUE}" readonly="readonly" />',
);
then you analyze each field and apply a default unless a known prefix is used.
Your users would then have to name the fields accordingly. Another possibility is to allow for a "meta-table" to hold the type and handling of each table and field, but in that case you would need to complicate a bit the user interface by creating a sort of "admin editor" for the Meta table:
table field type rw parameters
users name text yes
users id hidden no
users role text no
users notes area yes class:"widearea"
...and that way be dragons ORM frameworks.