Change the same field from all the tables from a particular database
Modify column by name(s):
you can also use any SQL Where, such as column_name in (...) or using other columns in 
 information_schema.columns table.

select  concat('alter table ',table_schema,'.',table_name,' change column ... ;') from information_schema.columns  where column_name='r_id'


use group_concat or similar and just copy/paste.