get avg time on site by gender

[whisher]

Hi,
I'm in a doubt is it right this query

SELECT A.domain_id AS domain_id, U.sesso AS field, NULL AS subfield, CAST( A.access_start_datetime AS DATE ) AS DATE, AVG( TIMESTAMPDIFF( 
MINUTE , A.access_start_datetime, A.access_end_datetime ) ) AS value
FROM stats_access A
JOIN users U ON U.id = A.fb_id
WHERE (
A.fb_id IS NOT NULL
)
GROUP BY A.domain_id, field, CAST( A.access_start_datetime AS DATE ) 

to get the avg time on site by gender ?
and how the group like
0-10 minutes
10-20 minutes
20-30 minutes
....

[whisher]

SELECT A.domain_id AS domain_id, U.sesso AS field, NULL AS subfield, 
CAST( A.access_start_datetime AS DATE ) AS DATE, 
CASE 
    WHEN AVG( TIMESTAMPDIFF( MINUTE , A.access_start_datetime, A.access_end_datetime ) ) <10
        THEN  '0-10'
    WHEN AVG( TIMESTAMPDIFF( MINUTE , A.access_start_datetime, A.access_end_datetime ) ) >11 <21
        THEN  '10-20'
    WHEN AVG( TIMESTAMPDIFF( MINUTE , A.access_start_datetime, A.access_end_datetime ) ) >21 <31
        THEN  '20-30'
    ELSE  '30+'
     END AS value
FROM sharint_stats_access A
JOIN sharint_users U ON U.id = A.fb_id
WHERE (A.fb_id IS NOT NULL)
GROUP BY A.domain_id, field, CAST( A.access_start_datetime AS DATE ) 

is it ok ?

[whisher]

SELECT A.domain_id AS domain_id, U.gender AS field, 
CAST( A.access_start_datetime AS DATE ) AS DATE, 
CASE 
    WHEN AVG( TIMESTAMPDIFF( MINUTE , A.access_start_datetime, A.access_end_datetime ) ) <10
        THEN  '0-10'
    WHEN AVG( TIMESTAMPDIFF( MINUTE , A.access_start_datetime, A.access_end_datetime ) ) >11 <21
        THEN  '10-20'
    WHEN AVG( TIMESTAMPDIFF( MINUTE , A.access_start_datetime, A.access_end_datetime ) ) >21 <31
        THEN  '20-30'
    ELSE  '30+'
     END AS subfield,
avg(timestampdiff(MINUTE,A.access_start_datetime,A.access_end_datetime)) AS value
FROM stats_access A
JOIN users U ON U.id = A.fb_id
WHERE (A.fb_id IS NOT NULL)
GROUP BY A.domain_id, field, CAST( A.access_start_datetime AS DATE ) 

better