How to convert Nvarchar column to INT

Question

I have a nvarchar column in one of my tables. Now I need to convert that column values to INT type..

I have tried using

cast(A.my_NvarcharColumn as INT)  

and

convert (int, N'A.my_NvarcharColumn') 

When I ran my query I am getting errors like

Conversion failed when converting the nvarchar value ' 23454542 ' to data type int.

hi i am posting my entire code snippet

SELECT A.objID, name, des,  right(Replace(Ltrim(Replace(substring(my_nvarcharcolumn,1,9), '0', ' ')), ' ', '0'),10) AS new_nvarcharcolumn  INTO #tmp1 FROM [database].[dbo].[tblname] AS A INNER JOIN (SELECT * FROM [database].[dbo].tblname1 WHERE sourceID = 32) AS AI ON source = A.objID INNER JOIN [database].[dbo].tblname2 AS I ON I.ObjectID = A.Source  SELECT MAX(m_dAddDate) AS date_Asof, dnum INTO #tmp2 FROM  (SELECT * FROM [database].[dbo].tblname WHERE senior <> '' AND class = 'SSS') AS A GROUP BY dnum  SELECT DISTINCT A.* INTO #tmp3 FROM #tmp1 AS A INNER JOIN #tmp2 AS SD ON SD.dnum =cast(A.new_nvarcharcolumn as INT) INNER JOIN database.[dbo].tbl4 AS M ON M.dnum = cast(A.new_nvarcharcolumn as INT)  AND SD.date_Asof = M.adddate 

Answer 1

CONVERT takes the column name, not a string containing the column name; your current expression tries to convert the string A.my_NvarcharColumn to an integer instead of the column content.

SELECT convert (int, N'A.my_NvarcharColumn') FROM A; 

should instead be

SELECT convert (int, A.my_NvarcharColumn) FROM A; 

Simple SQLfiddle here.