Question

i have about 12 tables i need to iterate thru and update all datetime fields (which is a varchar type) check if it’s a date and if so, add 5hrs to account for utc adjustment or if it’s an invalid date just set it to null. Below is a template I came up with. Just wondering if there are some other ways to do this?

update Tables_1
set releasedate = CASE ISDATE(releasedate) 
                     WHEN 1 THEN DATEADD(HH, 5, releasedate) 
                     ELSE NULL 
                  END,
    returndate = CASE ISDATE(returndate)
                     WHEN 1 THEN DATEADD(HH, 5, returndate) 
                     ELSE NULL 
                 END

given: sql server 2008, i know the columns and tables already that have the datetime type stored as varchar.

bonus request to add another check. If it is a date and the time is not specified, set the time to 5:00 AM

Answer 1

If they all end with date you could build it dynamically:

DECLARE @sql NVARCHAR(MAX) = N'';

SELECT @sql += ', ' + name = CASE ISDATE(' + name + ') WHEN 1 THEN 
      DATEADD(HOUR, 5, ' + name + ' ELSE NULL END'
FROM sys.columns 
WHERE name LIKE '%date' AND [object_id] = OBJECT_ID('dbo.Tables_1');

SELECT @sql = 'UPDATE dbo.Tables_1 SET ' + STUFF(@sql, 1, 1, N'');

PRINT @sql;
-- EXEC sp_executesql @sql;

Now if you want to do that for 12 tables, you could just do this in a loop, e.g.

DECLARE @t SYSNAME, @sql NVARCHAR(MAX);

DECLARE c CURSOR LOCAL STATIC FORWARD_ONLY READ_ONLY
FOR 
  SELECT name FROM sys.tables 
  WHERE name IN ('Tables_1' --, other tables
);

OPEN c;

FETCH NEXT FROM c INTO @t;

WHILE @@FETCH_STATUS = 0
BEGIN
    SELECT @sql = ', ' + name = CASE ISDATE(' + name + ') WHEN 1 THEN 
          DATEADD(HOUR, 5, ' + name + ' ELSE NULL END'
    FROM sys.columns 
    WHERE name LIKE '%date' AND [object_id] = OBJECT_ID(@t);

    SELECT @sql = 'UPDATE ' + @t + ' SET ' + STUFF(@sql, 1, 1, N'');

    PRINT @sql;
    -- EXEC sp_executesql @sql;

    FETCH NEXT FROM c INTO @t;
END

CLOSE c;
DEALLOCATE c;