Question

I have this

WITH sequenced_records AS (
    SELECT ROW_NUMBER() OVER (ORDER BY [DateTime] DESC) AS sequence_id, *
    FROM StreamView
    WHERE TypeOf = @TypeOf
    AND [DateTime] >= @DateTime
)
SELECT * FROM sequenced_records WHERE sequence_id = 1;

Which works fine for getting the latest record. But what if it doesn’t find anything? How can I get it to return the latest record going backwards? Meaning if there isnt any newer items than the given DateTime, it would instead go backwards and fetch the first item it find.

thanks

Answer 1

A couple of options:

1) If @@RowCount = 0 perform a separate select.

2) Select into a local table, then if that contains no rows, select into it using your new query, then select out of that table for returning data to caller.

And the separate select could be (haven’t tested this and not familiar with with statements, but here goes anyway):

WITH sequenced_records_one AS (
    SELECT TOP 1 ROW_NUMBER() OVER (ORDER BY [DateTime] DESC) AS sequence_id, *
    FROM StreamView
    WHERE TypeOf = @TypeOf
)
SELECT * FROM sequenced_records_one WHERE sequence_id = 1;

Upon further review, unless you have simplified this query a lot, you are doing too much work:

SELECT TOP 1
       * 
  FROM StreamView
 WHERE TypeOf = @TypeOf
   AND [DateTime] >= @DateTime
ORDER BY [DateTime] DESC

IF @@RowCount = 0
  BEGIN
      /* Get the first record created today */
    SELECT TOP 1
           *
      FROM StreamView
     WHERE TypeOf = @TypeOf
       AND [DateTime] >= CONVERT(DATE, GETDATE())
  ORDER BY [DateTime] ASC
  END