Question

So I have a base table that looks something like this.

SELECT [BILL_MONTH]
      ,[BILL_YEAR]
      ,[BILLED]
 FROM bill_Detail

Everything is varchar.

I created a view based on that table that converts the bill year and bill month to a datetime field. Of course, the bill_month and bill_year fields have some crap data that doesn’t convert so I have the following WHERE clause in my view definition.

WHERE   ISDATE(CONVERT(varchar(4), BILL_YEAR)  + '-' + CONVERT(varchar(3), BILL_MONTH) + '-1' ) = 1

The view works like a champ when I do a plain select on it. No bad dates, everything cleaned up, etc. However, when I try and do any sort of date arithmetic (dateadd, datediff) I start getting conversion errors.

EDIT: Adding in actual view and test select statement:

Code for the view

SELECT  ID
    ,BILLED
    ,Payment_Type
    ,CONVERT(datetime, CONVERT(varchar(4), BILL_YEAR)  + '-'  + CONVERT(varchar(3), BILL_MONTH) + '-1' ) 
    AS BillDate FROM    dbo.Detail AS d WHERE   ISDATE(CONVERT(varchar(4), BILL_YEAR)  + '-' + CONVERT(varchar(3), BILL_MONTH) + '-1' ) = 1 AND     ISNULL(Payment_Code,'') = '' AND        Payment_Type in ('D','I')

Here is the select statement that blows up.

SELECT ID
  ,[BILLED]
  ,[Payment_Type]
  ,[BillDate] FROM vw_DelinquentDetail where isdate(billdate) = 1

The select statement is where the following error pops up.

The conversion of a char data type to a datetime data type resulted in an out-of-range datetime value.

Sorry for the code formatting on the first section.

Answer 1

make sure you cast or convert the date to a datetime in the view:

create table testdates
(BILL_MONTH  varchar(3)
,BILL_YEAR   char(4)
,BILLED char(1)
)

insert into testdates values ('01','2009','y')
insert into testdates values ('02','2009','y')
insert into testdates values ('03','2009','y')
insert into testdates values ('a','bbb','n')

create view testdates_v as
select
CONVERT(datetime,CONVERT(varchar(4), BILL_YEAR)  + '-' + CONVERT(varchar(3), BILL_MONTH) + '-1') as billdate
from testdates
WHERE   ISDATE(CONVERT(varchar(4), BILL_YEAR)  + '-' + CONVERT(varchar(3), BILL_MONTH) + '-1' ) = 1
go

now try to use the view:

select billdate from testdates_v

OUTPUT:

billdate
-----------------------
2009-01-01 00:00:00.000
2009-02-01 00:00:00.000
2009-03-01 00:00:00.000

(3 row(s) affected)


select billdate+1,dateadd(mi,45,billdate) from  testdates_v

output:

----------------------- -----------------------
2009-01-02 00:00:00.000 2009-01-01 00:45:00.000
2009-02-02 00:00:00.000 2009-02-01 00:45:00.000
2009-03-02 00:00:00.000 2009-03-01 00:45:00.000

(3 row(s) affected)

EDIT after OP’s edit giving more code:

SQL SERVER is probably trying to build out the billdate column before it applies the WHERE. As a result, change your view to select billdate using a CASE, so it is NULL when not a valid date:

SELECT  ID
        ,BILLED
        ,Payment_Type
        ,CASE
             WHEN ISDATE(CONVERT(varchar(4), BILL_YEAR)  + '-' + CONVERT(varchar(3), BILL_MONTH) + '-1' ) = 1  THEN CONVERT(datetime, CONVERT(varchar(4), BILL_YEAR)  + '-'  + CONVERT(varchar(3), BILL_MONTH) + '-1' ) 
             ELSE NULL
         END AS BillDate 
    FROM    dbo.Detail AS d 
    WHERE   ISDATE(CONVERT(varchar(4), BILL_YEAR)  + '-' + CONVERT(varchar(3), BILL_MONTH) + '-1' ) = 1 AND         ISNULL(Payment_Code,'') = '' AND                Payment_Type in ('D','I')

using the above view, the error goes away.