Renumber table rows

Hello.

 

I have a table that his primary key is not ordered is something like this:

 

1      - a

12    - b

123  - c

etc.

 

I want to do an update to make it like this

 

1 – a

2 – b

3 – c

 

I tried this:

 

UPDATE operador SET idoperador=(SELECT row_number() OVER (ORDER BY idoperador) from operador)

 

But it returns this error: more than one row returned by a subquery used as an expression and I know that is because the substring returns more than one row, but how can I use the subquery to perform the update?.

 

Thank you in advance