Loop twice through a PHP / MYSQL result set

I get asked all the time if it is possible to loop multiple times through a MySQL result set in PHP. Here’s the answer.

First, you’ll need a MySQL result set. To do that you’ll need to select something from your database and loop through it like so:

$result = mysql_query("SELECT * FROM my_table");
while($row = mysql_fetch_assoc($result)) {
// inside the loop
}

The problem is, if you want to loop through the same result set again, you will get an error because the internal pointer is currently at the end of the result. You will need to put the pointer back at the beginning of the result set so that you can loop through it again.

You can do it with a helpful php function named mysql_data_seek.

mysql_data_seek($result, 0); // set the pointer of the result set back to the beginning.
while($row2 = mysql_fetch_assoc($result)) {
// inside the loop 
}

This demonstrates how, as a PHP website developer, you can reset the pointer of a MySQL result set, which will allow you to iterate through the result set for a second time.

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