在 SQL 服务器中转置日期时间记录

Question

I'm working with the following table in SQL Server, which captures the start & end date/time for which an employee worked:

EMP_NO  RECORD_DATE     START_TIME          END_TIME
123456  2020-07-04      10:00:00.0000000    14:30:00.0000000

I need to transpose the date/time values, so that it generates incremental records at 30 minute intervals with the Date/time values concatenated:

Expected Result:

EMP_NO  SHIFT_WORKED
123456  2020-07-04 10:00
123456  2020-07-04 10:30
123456  2020-07-04 11:00
123456  2020-07-04 11:30
123456  2020-07-04 12:00
123456  2020-07-04 12:30
123456  2020-07-04 13:00
123456  2020-07-04 13:30
123456  2020-07-04 14:00

Sample code:

CREATE TABLE #HOURS (
  EMP_NO INT NOT NULL,
  RECORD_DATE DATETIME ,
  START_TIME TIME NOT NULL, 
  END_TIME TIME   NOT NULL
) 

INSERT INTO #HOURS 
VALUES  (123456  ,' 2020-07-04',' 10:00',' 14:30') 

Answer 1

A tally table will help you here. (I prefer to call it an "integers table"). This is just a table of integers. You can either actually have one persisted somewhere in the database, or create one "one the fly" with a CTE. There are a lot of different ways to create such a thing, some faster than others!

Once you have a tally table, you can generate any values that can be mathematically derived from that. In your case, datetime values in 30 minute increments. You can then join that onto your date range. Here's one way which generates a tally table as a CTE

with integers as (
   select     top 1000 -- as many as you need
              i = -1 + row_number() over (order by a.number) -- start from 0
   from       master..spt_values  a
   cross join master..spt_values  b   
)
select      h.emp_no,
            shift_worked = dateadd(minute, i * 30, t.startdt)
from        #hours   h
cross apply (  -- this cross apply just makes the join to integers easier to read                   
                select startdt = h.record_Date + cast(h.start_Time as datetime),
                       enddt = h.record_date + cast(h.end_time as datetime)
            )        t
join        integers i on dateadd(minute, i * 30, t.startdt) < t.enddt

Answer 2

you can do this:

    CREATE TABLE temp (EMP_NO  INT ,SHIFT_WORKED datetime)
    DECLARE @START_TIME TIME,@END_TIME TIME,@shift TIME,@emp int
    SELECT @START_TIME=START_TIME,@END_TIME=END_TIME,@emp=EMP_NO FROM #HOURS
    SET @shift=@START_TIME
    WHILE DATEADD(MINUTE, 30, @shift) <=@END_TIME
    BEGIN
    INSERT INTO temp  VALUES(@EMP,@shift)
    SET @Shift = DATEADD(MINUTE, 30, @shift)
    END