android - Converting string to MySQL timestamp format in php

Question

I am writing a query in php using a string sent from a android java application.
The query is something like :

$insertSQL = sprintf("INSERT INTO app_DuckTag (taste) VALUES (%s) WHERE species=%s AND timestamp=%s",
                         GetSQLValueString($_POST['taste'], "text"),
                         GetSQLValueString($_POST['species'], "text"),
                         GetSQLValueString($_POST['timestamp'], "text"));

But I doubt timestamp is stored as a string inside MySQL.
How should I convert the string to time format as in MySQL?
The strtotime(string) php function converts it to unix time.
But the MySQL stores it differently, I guess. Thank you.

EDIT: This is how it shows up in MySQL phpmyadmin: 2011-08-16 17:10:45

EDIT: My query is wrong though. Cannon use a where clause with Insert into.
The query has to be UPDATE .... SET ... = ... WHERE ....
But the accepted answer is the correct way to use the time inside the WHERE clause.

Answer 1

This should be all:

date("Y-m-d H:i:s", strtotime($_POST['timestamp']));

if you want to check for timezones and such you should use strftime instead of date