I have a big database in which the
WHERE `website` LIKE 'http://.%';
UPDATE your_table SET your_field = REPLACE(your_field, 'http://.www', ' http://www') WHERE your_field LIKE '%http://.ww%';
The REPLACE function is the simplest way I know to do this and once you know it is there it is a very useful tool. In this case I guess you would not need the WHERE clause if it is a small number of records, but I would add it so you work on only subset of the data, better for larger data sets and to avoid unintended consequences.