SQL / Wordpress - query for removing a comment field

Does anyone know how can I replace the "comment_author_url" field from all comments by running a SQL query?

for example开发者_StackOverflow中文版 if this field is http://google.com to replace it with "" (empty string)

Use:

UPDATE your_table
   SET comment_author_url = ''
 WHERE comment_author_url = 'http://google.com'