Output variable from dynamic SQL - sql-server-2008

Question

I have an issue wen I try to output a value from a dynamic T-SQL Query inside of a stored procedure.
I try to execute the following and simply output a 1 if something was found:
SET NOCOUNT ON
DECLARE #returnValue int
DECLARE #Statement nvarchar(400)
set #Statement = 'SELECT #result=''1'' FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = ''sourceTable''
AND COLUMN_NAME = #columnIN
AND TABLE_SCHEMA = ''dbo'''
exec sp_executesql #Statement,
N'#columnIN nvarchar(60),#result INT OUTPUT',
#columnIN = #column, #result=#returnValue OUTPUT
select #returnValue
This currently yields NULL. Does anyone have any idea what I'm missing?
Additional Information:
The column that I try to lookup is for example column1 . If I run the SQL query with ...AND CLOUMN_NAME = 'column1' ... I get a 1 back.
If I print the #column variable in the SP I get 'column1'.
#column is declared as an input variable with nvarchar(60) in the SP: PROCEDURE [dbo].[usp_checkColumn] (#column nvarchar(60), #result INT OUTPUT)
As per request the complete SP here:
Create PROCEDURE [dbo].[usp_checkColumn] (#column nvarchar(60), #result INT OUTPUT)
AS
BEGIN
-- SET NOCOUNT ON added to prevent extra result sets from
-- interfering with SELECT statements.
SET NOCOUNT ON
DECLARE #returnValue int
DECLARE #Statement nvarchar(400)
set #Statement = 'SELECT #result=''1'' FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = ''t_table''
AND COLUMN_NAME = #columnIN
AND TABLE_SCHEMA = ''dbo'''
exec sp_executesql #Statement, N'#columnIN nvarchar(60),#result INT OUTPUT', #columnIN = #column, #result=#returnValue OUTPUT
select #returnValue
return #returnValue
END
And here's how I call the SP:
DECLARE fcursor CURSOR
FOR
select FieldName
from t_fieldDefinition
OPEN fcursor
Fetch next from fcursor into #field;
WHILE ##FETCH_STATUS = 0
BEGIN
SET #tmpField = '''' + #field + ''''
SET #field ='[' + #field + ']'
set #available = 0
exec usp_checkColumn #tmpField,#available OUTPUT
If I print the [#column] variable in the usp_checkColumn I do get the correct column inside of the ''. If I copy & paste the print of this variable and insert it into the query I get a 1 back, if I run the SP I get NULL(converted to 0 as NULL is not valid for the INT variable) back.
Here's the content of the t_fieldDefinition table:
FieldName ID
Source 5
column1 6
column2 7
Client 8
asd BSX 9
bsd 10
esd 11
esx 12
And here's the definition of the t_table table:
ID bigint Unchecked
Source varchar(250) Checked
column1 varchar(250) Checked
column2 nvarchar(100) Checked
Client varchar(10) Checked
asd varchar(250) Checked
[asd BSX] varchar(250) Checked
so that means that it should return 1 for all that are inside of the table definition and 0 for all others. Is it possible that the fields with a white space can be the issue? Although they work as well when you do it manually. It's not that I really have an option to change it but at least I would now the cause of the issue then.

Answer 1

I'm going to venture an answer on this.
I do not recommend using a cursor to go through each column just to test if the column exists in another table. If you insist on using a cursor, you could use a subquery to limit the results that you're cycling through to only the columns that don't exist in the other table, eliminating the need for the stored procedure that checks each individually (which by the way I think makes more sense as a user function):
DECLARE fcursor CURSOR
FOR
SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS
where table_name = 't_table' and not column_name in
(
SELECT COLUMN_Name FROM INFORMATION_SCHEMA.COLUMNS
where table_name = 't_fieldDefinition'
)
If your goal really is to alter the table to add any missing columns, then this can be improved by eliminating the cursor and outputting your results using FOR XML:
declare #sql varchar(max)
set #sql =
(
SELECT cast('ALTER TABLE t_fieldDefinition ADD [' + COLUMN_NAME + '] INT;' as varchar(max)) FROM INFORMATION_SCHEMA.COLUMNS
where table_name = 't_table' and not column_name in
(
SELECT COLUMN_Name FROM INFORMATION_SCHEMA.COLUMNS
where table_name = 't_fieldDefinition'
) FOR XML PATH ('')
)
print #sql
exec (#sql)