You just need basic date arithmetic, and the plain old date type. CREATE TABLE doctor_visits ( doctor_id NUMBER NOT NULL, in_time DATE NOT NULL, out_time DATE NOT NULL ) / I presume you want to find doctors who were in the hospital at 10:00am, as opposed to doctors who visited exactly at 10AM SELECT doctor_id … Read more
DateTime has perfect method to substract (actually add negative value) months from current date. For example: int ageInMonths = 18; DateTime dt = DateTime.Today; DateTime DateOfBirth = dt.AddMonths(-ageInMonths); solved Finding Date of Birth given age in months [closed]
If you really what to work only with the time element, the easiest way to so is to employ the ‘SSSSS’ date mask, which returns the number of seconds after midnight. So this query will return double the number of seconds between the two columns: select ( to_number(to_char(atn_inn, ‘sssss’)) – to_number(to_char(acn_inn, ‘sssss’)) ) * 2 … Read more
1) You need a semicolon and the end of your prototype: float xc(float frequency, float capacitance); 2) Variable declarations don’t have “()” float f; float c; 3) arguments are separated by commas: capreac = xc(f, c); 4) argument names should match variable names: float xc(float frequency, float capacitance); { float answer; answer = (1.0/(2.0*pi*capacitance*frequency)); … … Read more
You can generate all starts of months with generate_series(), then bring the table with a left join: select to_char(d.start_date, ‘mon’) as month, extract(month from d.start_date) as month_num, sum(cost_planned) filter (where t.aasm_state in (‘open’, ‘planned’ ) ) as planned, sum(cost_actual) filter (where t.aasm_state=”closed”) as actual from generate_series(‘2020-01-01’::date, ‘2020-12-01’::date, ‘1 month’) d(start_date) left join activity_tasks t on … Read more