INSERT INTO command doesn't work - sql

Question

I have one outer cursor and one inner cursor also have two tables to work with. Now with the outer cursor i'm making new columns in the table 1 and naming them by the values from the table two, and that works just fine. Problem is with the inner cursor witch i used to insert the values into those new columns from one specific column from another table. This seams not to work, but what confusing me is that i do not get any error messages. Now i hope you understand what i'm trying to do, here is the code so comment for more description about the problem :
DECLARE #rbr_param nvarchar(255)
DECLARE #vrednost nvarchar(255)
DECLARE #cName nvarchar(255)
DECLARE #sql nvarchar (255)
DECLARE curs CURSOR FOR SELECT DISTINCT rbr_param FROM dbo.parametri_pomocna ORDER BY rbr_param
OPEN curs
FETCH NEXT FROM curs
INTO #rbr_param
WHILE ##FETCH_STATUS = 0
BEGIN
SET #cName = 'P_'+#rbr_param+'_P'
EXEC('ALTER TABLE dbo.Parametri ADD ' + #cName + ' nvarchar(255)')
DECLARE vrd CURSOR FOR SELECT DISTINCT vrednost FROM dbo.parametri_pomocna
OPEN vrd
FETCH NEXT FROM vrd
INTO #vrednost
WHILE ##FETCH_STATUS = 0
BEGIN
SET #sql = 'INSERT INTO dbo.Parametri'+(#cName)+ ' SELECT vrednost FROM dbo.parametri_pomocna WHERE vrednost = '+#vrednost+ ' AND rbr_param = '+#rbr_param
if exists (select * from INFORMATION_SCHEMA.COLUMNS where table_name = 'dbo.Parametri' and column_name = '#cName')
begin
exec(#sql)
end
FETCH NEXT FROM vrd
INTO #vrednost
END --end vrd
CLOSE vrd
DEALLOCATE vrd
FETCH NEXT FROM curs
INTO #rbr_param
END
CLOSE curs
DEALLOCATE curs

Answer 1

You have two problems here:
if exists ( select * from INFORMATION_SCHEMA.COLUMNS
where table_name = 'dbo.Parametri'
and column_name = '#cName'
)
(1) This view will never have table_name = schema name and table name.
(2) You have enclosed your variable name in single quotes for some reason.
For both of these reasons, your IF condition will never return true.
Try:
IF EXISTS
(
SELECT 1 FROM sys.columns
WHERE [object_id] = OBJECT_ID('dbo.Parametri')
AND name = #cName
)
(And here is why I prefer catalog views over INFORMATION_SCHEMA.)
Also this double-nested cursor thing seems quite inefficient and a lot more code than necessary to achieve what I think you're trying to do. How about something like this instead:
DECLARE #sql NVARCHAR(MAX);
SET #sql = N'';
SELECT #sql = #sql + N'ALTER TABLE dbo.Parametri ADD '
+ QUOTENAME('P_' + rbr_param + '_P') + ' NVARCHAR(255);'
FROM dbo.parametri_pomocna GROUP BY rbr_param;
EXEC sp_executesql #sql;
SET #sql = N'';
SELECT #sql = #sql + N'INSERT dbo.Parametri('+QUOTENAME('P_' + rbr_param + '_P')+ ')
SELECT vrednost
FROM dbo.parametri_pomocna WHERE rbr_param = ''' + rbr_param + '''
GROUP BY vrednost;'
FROM dbo.parametri_pomocna
GROUP BY rbr_param;
EXEC sp_executesql #sql;