Data validation in sql

I need to validate a column having time ranges like '8:00 am - 9:00 pm' I n开发者_如何转开发eed to split this column into two and update to my table with the date with current date but the time from the range for example "2011-05-23 08:00:00" And "2011-05-23 21:00:00" for the range record. kindly help. Also I need to process if the data is '8:00 a.m. - 9:00 p.m.', '8:00 a.m - 9:00 p.m' or '8:00 am - 12:00 noon'. If there is no "-" need to reject the data for the record.

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Here's a basic solution, which, I think, could well be used as a starting point:

DECLARE @Today datetime = CAST(GETDATE() AS date);

WITH datasource (TimeRange) AS (
  SELECT '10 a.m. - 1 p.m.' UNION ALL
  SELECT '8 am - 12 noon' UNION ALL
  SELECT '12 noon - 4 p.m.' UNION ALL
  SELECT '9 - 10 am' UNION ALL
  SELECT '10 am 1 pm'
),
HyphensIncluded AS (
  SELECT *, HyphenPos = CHARINDEX('-', TimeRange)
  FROM datasource
  WHERE CHARINDEX('-', TimeRange) > 0
),
Split AS (
  SELECT
    *,
    StartTimeStr = REPLACE(
      REPLACE(
        LTRIM(RTRIM(SUBSTRING(TimeRange, 0, HyphenPos))),
        '.',
        ''
      ),
      'noon',
      'pm'
    ),
    EndTimeStr = REPLACE(
      REPLACE(
        LTRIM(SUBSTRING(TimeRange, HyphenPos + 1, LEN(TimeRange) - HyphenPos)),
        '.',
        ''
      ),
      'noon',
      'pm'
    )
  FROM HyphensIncluded
),
Validated AS (
  SELECT *
  FROM Split
  WHERE ISDATE(StartTimeStr) = 1
    AND ISDATE(EndTimeStr) = 1
)
SELECT
  StartTimestamp = @Today + StartTimeStr,
  EndTimestamp   = @Today + EndTimeStr
FROM Validated

Output:

StartTimestamp          EndTimestamp
----------------------- -----------------------
2011-05-23 10:00:00.000 2011-05-23 13:00:00.000
2011-05-23 08:00:00.000 2011-05-23 12:00:00.000
2011-05-23 12:00:00.000 2011-05-23 16:00:00.000

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it can be implemented using a trigger. Use 24H time format to avoid dealing with AM/PM.