Find and Replace text in all table using mysql query
MySQL's replace function should come handy to replace the text you need:

update $table set column = replace(column, 'old_text', new_text') where column='old_text' and &lt;other_conditions&gt;;

Now, as you talk of replace in all tables, that's something not possible in single query. Though you can create a routine to do so!
For the sample you can refer a procedure which is finding a string in all tables of all databases.


(Though been already mentioned in comments) table_schema is a column name of information_schema.tables table which represents the database name.