And the database is MySQL?
You can do this with the help of the INFORMATION_SCHEMA database.
You can ask it for all the tables in your own database:
select table_name from tables where table_schema = 'name of your database';
Then you can ask for all the columns in a given table:
select column_name, data_type from columns where table_schema='db name' and table_name='one of your tables'
and then you can go look in all the columns that are text or varchar or char (and are long enough to hold that text) in your actual tables and do a REPLACE that zaps that text.
Write a little script (PHP or whatever you are familiar with) to run through all the tables and all the columns that are of the right type.