hashtable to pass to proc

[Guest]

I took over an web app (C#) were the developer put everything in a has table
then called a method to execute a stored procedure, now I'm running into some
issues were if I do an update and a NULL is passed that the field in the db
is left empty and NULL is not entered in. So how can I pass a NULL value in a
hashtable, execute the stored procedure and have NULL entered in the table
instead of a blank field?

here is an example of the code:
the call to the stored procedure and passing parameters:

private voide UpdateCars(string Make, string Model, string Notes)
{
string sql = "spUpdateCars";
System.Collections.HashTable params = new System.Collections.HashTables();
params.add("@make", Make);
params.add("@model", Model);
params.add("@notes", Notes);

this.executeStoredProcedureNonQuery(strSQL, params)

}

now the executeStoredProcedureNonQuery method:
protected int executeStoredPorcedureNonQuery(string sqlCommand ,
System.Collections.Hashtable parameters)
{
int result = 0 ;

SqlConnection conn = getConnection() ;
try
{
SqlCommand cmd = new SqlCommand(sqlCommand, conn) ;
cmd.CommandType = CommandType.StoredProcedure ;
foreach (DictionaryEntry parameterEntry in parameters)
{
cmd.Parameters.Add((string)parameterEntry.Key, parameterEntry.Value) ;

}

cmd.Connection.Open() ;
result = cmd.ExecuteNonQuery() ;
cmd.Connection.Close() ;
}
catch(SqlException e)
{
Console.Write(e.StackTrace) ;
}
finally
{
if (conn != null)
conn.Close() ;
}

return result ;
}

so how can i get it to enter NULL in the field and not leave it blank?

 

[Peter Rilling]

Maybe you could set the HT value to DbNull, or just have a conditional
statement when you build the SqlCommand where if the value is null, then
insert DbNull. Either way you are using DbNull.

 

[Guest]

I've tried that and still passing in blank and not NULL to the table.
I did something like;
if(parameterEntry.value == "")
{
parameterEntry.value = System.DBNull.value;
}

and it would not pass NULL to the table, i even checked on the web form
itself,
if (make.text == "")
{
make.text = System.DBNull.value;
}

and still nothing,

 

[Peter Rilling]

Have you checked to see if it is a problem with the stored procedure? Maybe
the SP has the code to convert nulls into empty strings. Maybe that field
cannot handle nulls.

 

[Guest]

The field in the table allows NULLS.

The procs looks like this
create procedure spUpdateCars
{
@salesID int,
@make char(25) = NULL,
@model char(20) = NULL,
@notes varchar(250) = NULL
},
update Cars
set
CarMake = @make,
CarModel = @model,
SaleNotes = @notes
where sales ID = @salesID


is this how it should look to allow NULLS and insert NULL in the table or no?