Varchar to Numeric Exception - sql-server

Question

I realize this has been asked a million times, but I can't find an answer that works. New to sql server and vs 2010 vb (complain to the boss, not me), doing practice runs. Continually getting a varchar to numeric exception in the following:
Dim height, width As Decimal
height = InputBox("Enter height:")
width = InputBox("Enter width:")
'PRODUCING VARCHAR TO NUMERIC EXCEPTION
command = New SqlCommand("DECLARE #height as decimal(10,2), " & _
"#width as decimal(10,2), " & _
"#area as decimal(10,2); " & _
"SET #height = ' " & height & " '; " & _
"SET #width = ' " & width & " '; " & _
"SET #area = #height * #width; " & _
"IF #height IS NULL OR #width IS NULL " & _
" SELECT 'Either the height or width field was blank.' " & _
"ELSE IF #height <= 0 OR #width <= 0 " & _
" SELECT 'That''s some fancy negative space.' " & _
"ELSE " & _
" SELECT 'The area is: ' +#area;" _
, connect)
connect.Open()
rdr = command.ExecuteReader()
I have verified via vartype() that the data being passed is indeed decimal (I'm the only one testing, so not worried about that error control atm). I have tried using the variables with and without the enclosing single quotes. Cast() and Convert() are not working (unless I'm doing them incorrectly?). Not sure where the problem is?

Answer 1

Dim height, width As Decimal
height = InputBox("Enter height:")
width = InputBox("Enter width:")
'PRODUCING VARCHAR TO NUMERIC EXCEPTION
command = New SqlCommand("IF #height IS NULL OR #width IS NULL " & _
" SELECT 'Either the height or width field was blank.' " & _
"ELSE IF #height <= 0 OR #width <= 0 " & _
" SELECT 'That''s some fancy negative space.' " & _
"ELSE " & _
" SELECT 'The area is: ' + cast(#width * #height as varchar(20))" _
, connect)
command.Parameters.Add("#height", SqlDbType.Decimal).Value = height
command.Parameters.Add("#width", SqlDbType.Decimal).Value = width
connect.Open()
rdr = command.ExecuteReader()
Also, it's very strange to write IF/ELSE statements in SQL to choose among various selects. For SQL, you want to think in terms of writing a single statement that describes a set of data.