如何编辑此mySQL查询以不选择2列中具有相同值的行？

Question

Running the following query I get the following message

invalid use of group by

SELECT COUNT( id ) AS pages,
       hash, MIN( DATE( TIMESTAMP ) ) AS FirstVisit, 
       MAX( DATE( TIMESTAMP ) ) AS LastVisit
       FROM behaviour
       WHERE MIN( DATE( TIMESTAMP ) ) != MAX( DATE( TIMESTAMP ) )
       GROUP BY hash

How can I edit this query so as to not show the rows that FirstVisit equals LastVisit ?

Answer 1

Aggregate function can't be used in where clause, but can be used in having`.

Try this:

SELECT
     COUNT( id ) AS pages,
     hash,
     MIN( DATE( TIMESTAMP ) ) AS FirstVisit,
     MAX( DATE( TIMESTAMP ) ) AS LastVisit
FROM behaviour 
GROUP BY hash
HAVING MIN( DATE( TIMESTAMP ) ) != MAX( DATE( TIMESTAMP ) )