UPDATE one table column based on another table's column

In one table I have fields

  cat_id, cat_name

the table I need to update has several columns but I only want to update one based on the info in the new one.

 category

I would like to update the category field to the cat_id of the corresponding name.

in o开发者_StackOverflow中文版ther word

 IF 
 cat_id='66' and cat_name='STACKOVER'
 and
 category='STACKOVER'

The result should be

 category='66'

I'm not sure where to start..

If I understood you,

UPDATE new_category,category SET new_category.category=category.cat_id WHERE new_category.category=category.cat_name

should do the job and lead you toward understanding multi-table updates.