Search + Replace, Append, Prepend MySQL

Search and replace

update [table_name] set [field_name] = replace([field_name],'[string_to_find]','[string_to_replace]');

Append

update [table_name] set [field_name] = concat([field_name],'[string_to_append]');

Prepend

update [table_name] set [field_name] = concat('[string_to_prepend]',[field_name]);