how to find and replace a word in a mysql column?

Run a query like this to update in the same column:

UPDATE table 
   SET column = REPLACE(column, 'Street', 'St');

So, if i understand correctly, you want to modify the data on the database based on wether or not you're using the word street. I think this is the call u need.

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

I think this is the method you need to use, so your ending code will look something like

update myTable set address = replace(address,'street','St');

Is this what you meant?