Show that DAIMA

Single operating accept personnel action code number operation time
123456789 A, 501 E 2020/9/28 9:40
123456789 A, 501 B 2020/9/28 as
123456789 A 502 B 2020/9/28 will
123456789 A C 501 2020/9/28 he
123456789 C A 502 2020/9/28 wilt thou
123456789 A, 501 D 2020/9/28 double-break
123456789 D A 502 2020/9/28 they

Ask, need to compute accept staff B, C, D processing time, action 502 time minus the action time of 501, excuse me how to achieve the following effects: SQL

Accept the personnel handling time
0.006 B
C 0.007
D 0.042