MySQL Updating a specific Field
If you have two tables with a common key (in the case below it is the primary key "id"), it is possible to update a field in one of two tables (update_table) using data the second (reference_table) using a join.
The SQL code looks like this:
UPDATE update_table, reference_table SET update_table.field=reference_table.fieldref WHERE update_table.id=reference_table.id