Вычислить оставшиеся интервалы времени (дата начала -> дата окончания) после вычитания других интервалов времени

Question

Следующий скрипт вычисляет оставшиеся временные интервалы после вычитания других определенных временных интервалов.

В конце концов мне остается интервал, заполненный пробелами.

Вот сценарий, который я создал.Кто-нибудь знает лучший способ сделать это?

        SELECT * FROM SuspensionPeriod susPer WHERE id_document = 564148

DECLARE @idDocument BIGINT, @docBeginDate DATETIME, @docEndDate DATETIME

SET @idDocument = 564148

SELECT @docBeginDate = start_date, @docEndDate = end_date FROM Document md WHERE md.id_document = @idDocument

SELECT RowNum = Row_number() OVER(ORDER BY suspended_from), *
INTO   #SuspensionPeriods
FROM   SuspensionPeriod susPer WHERE susPer.id_document = @idDocument

DECLARE @MaxRownum INT

SET @MaxRownum = (SELECT Max(RowNum) FROM   #SuspensionPeriods)

DECLARE @Iter INT

SET @Iter = (SELECT Min(RowNum) FROM   #SuspensionPeriods)

DECLARE @intervalBegin DATETIME, @intervalEnd DATETIME

WHILE @Iter <= @MaxRownum
  BEGIN

      IF @Iter = 1
        BEGIN
            SET @intervalBegin = @docBeginDate
            SELECT @intervalEnd = suspended_from FROM   #SuspensionPeriods WHERE  RowNum = @Iter

            print dbo.fnFormatDate(@intervalBegin,'yyyy.MM.dd')
            print dbo.fnFormatDate(@intervalEnd,'yyyy.MM.dd')
            print '============================='


            --SELECT @intervalBegin = suspended_until FROM   #SuspensionPeriods WHERE  RowNum = @Iter
            --SELECT @intervalEnd = suspended_from FROM   #SuspensionPeriods WHERE  RowNum = @Iter + 1

            --print dbo.fnFormatDate(@intervalBegin,'yyyy.MM.dd')
            --print dbo.fnFormatDate(@intervalEnd,'yyyy.MM.dd')
            --print '============================='
        END

      IF @Iter <> 1 AND @Iter <> @MaxRownum
        BEGIN
            SELECT @intervalBegin = suspended_until FROM   #SuspensionPeriods WHERE  RowNum = @Iter - 1
            SELECT @intervalEnd = suspended_from FROM   #SuspensionPeriods WHERE  RowNum = @Iter 

            print dbo.fnFormatDate(@intervalBegin,'yyyy.MM.dd')
            print dbo.fnFormatDate(@intervalEnd,'yyyy.MM.dd')
            print '============================='


            SELECT @intervalBegin = suspended_until FROM   #SuspensionPeriods WHERE  RowNum = @Iter
            SELECT @intervalEnd = suspended_from FROM   #SuspensionPeriods WHERE  RowNum = @Iter + 1

            print dbo.fnFormatDate(@intervalBegin,'yyyy.MM.dd')
            print dbo.fnFormatDate(@intervalEnd,'yyyy.MM.dd')
            print '============================='
        END

      IF @Iter = @MaxRownum
        BEGIN
            --SELECT @intervalBegin = suspended_until FROM   #SuspensionPeriods WHERE  RowNum = @Iter - 1
            --SELECT @intervalEnd = suspended_from FROM   #SuspensionPeriods WHERE  RowNum = @Iter

            --print dbo.fnFormatDate(@intervalBegin,'yyyy.MM.dd')
            --print dbo.fnFormatDate(@intervalEnd,'yyyy.MM.dd')
            --print '============================='

            SELECT @intervalBegin = suspended_until FROM   #SuspensionPeriods WHERE  RowNum = @Iter
            SELECT @intervalEnd = @docEndDate 

            print dbo.fnFormatDate(@intervalBegin,'yyyy.MM.dd')
            print dbo.fnFormatDate(@intervalEnd,'yyyy.MM.dd')
            print '============================='
        END
      -- run your operation here
      SET @Iter = @Iter + 1
  END

DROP TABLE #SuspensionPeriods 

Answer 1

Как насчет

SELECT MIN(md.start_date), MIN(sp.suspended_from)
    FROM Document md
    JOIN SuspensionPeriod sp ON sp.id_document = md.id_document
    WHERE md.id_document = @idDocument
UNION
SELECT sp.suspended_to, (SELECT COALESCE(MIN(spnext.suspended_from), md.end_date) FROM SuspensionPeriod spnext WHERE sp.id_document=spnext.id_document AND spnext.suspended_from > sp.suspended_to)
    FROM Document md
    JOIN SuspensionPeriod sp ON sp.id_document = md.id_document
    WHERE md.id_document = @idDocument