Problem converting CHAR to DATETIME

hello all,

I am having a problem calculating the difference, in days, between two dates, STARTDATE and ENDDATE. The data is stored in the database as char(8), formatted YYYYMMDD. "Null" values are stored as '00000000'. When I try to use DATEDIFF an exception is thrown: "the conversion of a char data type to a datetime data type resulted in an out-of-range datetime value"

How can I fix this, and a get a result even if STARTDATE or ENDDATE is '00000000'? Changing the format of the stored data is not an option.

Thanks for any assistance.

Mike



CREATE TABLE dbo.DATETIME1 (
ID1 int,
STARTDATE char(8),
ENDDATE char(8)
)
INSERT into DATETIME1 (ID1, STARTDATE, ENDDATE)
VALUES (
1, '20070105', '20070108'
)
INSERT into DATETIME1 (ID1, STARTDATE, ENDDATE)
VALUES (
2, '20070105', '00000000'
)
Select * from DATETIME1
Select DATEDIFF(d, STARTDATE, Convert(datetime,ENDDATE) ) as Difference
from DATETIME1
WHERE ID1 = 1How about a case statement to check for the '00000000'? Or an isdate check?|||Ahhhh, good idea...can you help with the syntax of the CASE statement in SQA? I've done them in VB.NET, but not directly in SQL.

Thanks|||add this to your test code replacing your datediff select.


select STARTDATE, ENDDATE,
CASE
WHEN isdate(ENDDATE) = 0
THEN 0
ELSE
DATEDIFF(d, STARTDATE, Convert(datetime,ENDDATE) )
END
from DATETIME1 as DaysDifference|||THANKS! I was doing something similar, but couldn't quite get it to work! :D|||You could also try the following:
ISNULL(DATEDIFF(d, CONVERT(DATETIME, STARTDATE, 112), CONVERT(DATETIME, NULLIF(ENDDATE, '00000000'), 112), 0)
Btw: explicit conversions are always better than implicit ones:)