Search and replace within a column in mysql

In my codeigniter project I need to add slug field in the database from name column. This is what i did –

First of all i created a field name “slug” just after ename column and copied that content of ename to slug, using this query-

UPDATE default_event
SET `slug` = `ename`;

Then i fire this query to replace blank spaces with “-” to form links-

UPDATE default_event
SET slug = replace(slug, ‘ ‘, -‘);