hello i have databses and tables in mysql db...
i want to auto suggest databases name in a input box after depending on database string i want to auto suggest the tables inside that database....how could i do this?

You'll need to watch the input box with javascript, and on each change (or after x number of characters), use ajax to send the search string to a php script. That php script can query the database and return results to the ajax call, which can populate a list of possibilities.

To save on the amount of database queries being run as the end user types, you may want to pull all possible options form the database and put them in to an array and query that array instead of the database.