Попробуйте это:
Схема таблицы:
CREATE TABLE A(id INT, session_id INT,Event VARCHAR(20), created DATETIME);
INSERT INTO A VALUES(1, 101,'Start','2010/10/01 9:30:10')
,(2, 102,'Start' , '2010/10/01 9:31:10')
,(3, 101,'End' , '2010/10/01 9:32:10')
,(4, 103,'Start' , '2010/10/01 9:35:10')
,(5, 102,'End' , '2010/10/01 9:38:10')
,(6, 103,'End' , '2010/10/01 9:39:10')
,(7, 101,'Start' , '2010/10/01 9:39:10')
,(8, 102,'Start' , '2010/10/01 9:39:10')
,(9, 101,'End' , '2010/10/01 9:55:10');
Запрос:
SELECT D.session_id
,TIMESTAMPDIFF(MINUTE,MIN(D.created), MAX(D.created)) time_count
FROM(
SELECT a.id,a.session_id,a.created
,ROUND(count(*)/2,0) as RN
,count(*) as row_number1
FROM a AS a
JOIN a AS b ON a.session_id = b.session_id AND a.id >= b.id
GROUP BY a.id,a.session_id,a.created
ORDER BY 2,3
)D
GROUP BY D.session_id,D.RN
HAVING COUNT(1)>1
Выход:
session_id time_count
101 2
102 7
103 4
101 16
Fiddle:
Проверьте вывод в # SQL Fiddle