Use the following command to search and replace specific data in a specific column in a table.
update my_specific_table set my_specific_table_column = replace(my_specific_table_column, 'XXXXX' , 'AAAAA')
It is important to run this SQL command in PHPMYADMIN as a SQL QUERY. You will be able to simulate this query before running the actual update.
my_specific_table = Table where the search/replace will be performed
my_specific_table_column = Column within the specific table, where the search/replace will be performed.
XXXXX = is the string to search for
AAAAA = is the new string which will replace the old string