Conversion failed when converting the varchar to data type int - sql

Question

I have this query, I need to save Pubname, ISBNname, copiesname and createdname as Integers
DECLARE #a Table(bkID INT, bkname varchar(100), bkpub INT, bkISBN INT, bkcopies INT, bkcreatedby INT)
INSERT INTO #a (bkID, bkname, bkpub, bkISBN, bkcopies, bkcreatedby)
SELECT A.nameID,
A.bkname,
CAST((B.Pubname) AS INT),
CAST((C.ISBNname) AS int),
CAST((D.copiesname) AS int),
CAST((F.createdname) AS int)
FROM #bkname AS A
LEFT JOIN #bkPub AS B
ON (A.nameID = PubID)
LEFT JOIN #bkISBN AS C
ON (A.nameID = C.ISBNID)
LEFT JOIN #bkcopies AS D
ON (A.nameID = D.copiesID)
LEFT JOIN #bkcraeted AS F
ON (A.nameID = F.craetedID)
It returns this error:
Msg 245, Level 16, State 1, Procedure LR_InsertBookArray, Line 46
[Batch Start Line 2] Conversion failed when converting the varchar
value ''3' to data type int.

Answer 1

It seems highly unlikely that columns called name are actually integers in disguise. My guess is that you simply want the ids from the reference table, but your question doesn't have enough information to know if that is true.
In the meantime, you can use TRY_CAST():
TRY_CAST(B.Pubname AS int),
TRY_CAST(C.ISBNname AS int),
TRY_CAST(D.copiesname AS int),
TRY_CAST(F.createdname AS int)
This will return NULL if the values cannot be converted -- but it avoids the error.