update [table_name] set [field_name] = replace([field_name],'[string_to_find]','[string_to_replace]');
The world's most popular open source database[1] MySQL is a relational database management system, or RDBMS. Basically it's a software package that is very good at the organization and management...
IIRC mysql5 supports import of mysql4 data and structures natively (you can use mysql4 compatability when exporting sql data from phpmyadmin)
If not replaced having it resurfaced is recommended.
Posseses. Owns.
You don't have to but it would be wise to do so especially if the system over heated because of lost coolant.