Oracle 11g Release 2

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CREATE TABLE Events(
    EventID int,
    EventName varchar(20),
    EventTime numeric(17,6)
);
INSERT INTO Events VALUES (1, 'Event1_Start', 0.2);
1 rows affected

INSERT INTO Events VALUES (2, 'Event2_Start', 0.3);
1 rows affected

INSERT INTO Events VALUES (3, 'Event3_End', 0.2);
1 rows affected

INSERT INTO Events VALUES (4, 'Event2_End', 0.6);
1 rows affected

INSERT INTO Events VALUES (5, 'Event4_Start', 0);
1 rows affected

INSERT INTO Events VALUES (2, 'Event2_Start', 0.3);
1 rows affected

INSERT INTO Events VALUES (6, 'Event1_End', 0);
1 rows affected

select substr(eventname, 1, 6), sum(eventtime) from events group by substr(eventname, 1,6)


SUBSTR(EVENTNAME,1,6)
SUM(EVENTTIME)


Event2
1.2

Event4
0

Event3
.2

Event1
.2