using CASE in the WHERE clause

Solution 1:

You don't have to use CASE...WHEN, you could use an OR condition, like this:

WHERE
  pw='correct'
  AND (id>=800 OR success=1) 
  AND YEAR(timestamp)=2011

this means that if id<800, success has to be 1 for the condition to be evaluated as true. Otherwise, it will be true anyway.

It is less common, however you could still use CASE WHEN, like this:

WHERE
  pw='correct'
  AND CASE WHEN id<800 THEN success=1 ELSE TRUE END 
  AND YEAR(timestamp)=2011

this means: return success=1 (which can be TRUE or FALSE) in case id<800, or always return TRUE otherwise.

SELECT *
FROM logs
WHERE pw='correct'
  AND CASE
          WHEN id<800 THEN success=1
          ELSE 1=1
      END
  AND YEAR(TIMESTAMP)=2011