Write a query in SQL to count the number of patients who booked an appointment with at least one physician.
Sample table: appointment
appointmentid | patient | prepnurse | physician | start_dt_time | end_dt_time | examinationroom
---------------+-----------+-----------+-----------+---------------------+---------------------+-----------------
13216584 | 100000001 | 101 | 1 | 2008-04-24 10:00:00 | 2008-04-24 11:00:00 | A
26548913 | 100000002 | 101 | 2 | 2008-04-24 10:00:00 | 2008-04-24 11:00:00 | B
36549879 | 100000001 | 102 | 1 | 2008-04-25 10:00:00 | 2008-04-25 11:00:00 | A
46846589 | 100000004 | 103 | 4 | 2008-04-25 10:00:00 | 2008-04-25 11:00:00 | B
59871321 | 100000004 | | 4 | 2008-04-26 10:00:00 | 2008-04-26 11:00:00 | C
69879231 | 100000003 | 103 | 2 | 2008-04-26 11:00:00 | 2008-04-26 12:00:00 | C
76983231 | 100000001 | | 3 | 2008-04-26 12:00:00 | 2008-04-26 13:00:00 | C
86213939 | 100000004 | 102 | 9 | 2008-04-27 10:00:00 | 2008-04-21 11:00:00 | A
93216548 | 100000002 | 101 | 2 | 2008-04-27 10:00:00 | 2008-04-27 11:00:00 | B
Sql programming
Sample Output:
No. of patients taken at least one appointment ------------------------------------------------ 4 (1 row)need an explanation for this answer? contact us directly to get an explanation for this answer