Conversion failed when converting the varchar value 'null' to data type int.

Hello Experts,

I have the following SQL quaery, that is giving me:

Msg 245, Level 16, State 1, Line 1
Conversion failed when converting the varchar value 'null' to data type int.

However, if I remove the second-last line it works fine.

Reffering to the second-last line, [tblVouchers].fldVouchID is defined as primary key int auto increment, so it can never be null.

When I run this query in SQL server management studio it "executes with errors" reffering to the above.

Any ideas?
SELECT [vouch].fldDealName, [purch].fldVouchNumber,
 ([inv].fldFName + ' ' + [inv].fldLName) AS fldPurchBy,
 [inv].fldTransDate, [inv].fldTransTime,
 [purch].fldRedeemComment, [purch].fldRedeemed, [purch].fldRedeemDateTime 
FROM tblUsers AS users, 
 tblVouchers AS vouch, 
 tblPurchases AS purch, 
 tblInvoices AS inv
WHERE [purch].fldInvID = [inv].fldInvID 
AND [inv].fldRespCode < 50
AND [purch].fldVouchRecID = [vouch].fldVouchID 
AND [vouch].fldBizID = [users].fldUserID 
AND [users].fldUserID = 18 
AND [vouch].fldVouchID = 11
ORDER BY [inv].fldTransDate DESC, [inv].fldTransTime DESC

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APD TorontoAsked:
Who is Participating?
 
Raja Jegan RConnect With a Mentor SQL Server DBA & ArchitectCommented:
Try this one:
SELECT [vouch].fldDealName, [purch].fldVouchNumber,
 ([inv].fldFName + ' ' + [inv].fldLName) AS fldPurchBy,
 [inv].fldTransDate, [inv].fldTransTime,
 [purch].fldRedeemComment, [purch].fldRedeemed, [purch].fldRedeemDateTime 
FROM tblUsers AS users, 
 tblVouchers AS vouch, 
 tblPurchases AS purch, 
 tblInvoices AS inv
WHERE [purch].fldInvID = [inv].fldInvID 
AND [inv].fldRespCode < 50
AND [purch].fldVouchRecID = CAST(ISNULL([vouch].fldVouchID, '0') AS INT)
AND [vouch].fldBizID = [users].fldUserID 
AND [users].fldUserID = 18 
AND CAST(ISNULL([vouch].fldVouchID, '0') AS INT) = 11
ORDER BY [inv].fldTransDate DESC, [inv].fldTransTime DESC

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0
 
APD TorontoAuthor Commented:
OK, worked.

Could you please explain to me what it means

AND CAST(ISNULL([vouch].fldVouchID, '0') AS INT) = 11
0
 
Raja Jegan RSQL Server DBA & ArchitectCommented:
>> Conversion failed when converting the varchar value 'null' to data type int.

I have exactly worked to fix the above error.
Since you pass int value 11 as input to fldVouchID column, it tries to implicitly convert that column to int and in case of any null values it was erroring.
So, I first converted Null to '0' and then converted it to int explicitly so that the conversion will never fail..

Or you can also try the simpler version like

AND [vouch].fldVouchID = 11
0
 
APD TorontoAuthor Commented:
Thank You
0
 
Raja Jegan RSQL Server DBA & ArchitectCommented:
Welcome..
0
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