I believe that what you need is the System.DBNull value rather than
SqlString.Null.
Jon Stonecash
>From: Markus ESSMAYR <[EMAIL PROTECTED]>
>Reply-To: dotnet discussion <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Subject: [DOTNET] SqlString.Null?
>Date: Fri, 12 Apr 2002 11:05:47 +0200
>
>hello!
>
>i had the following line in my program
>
>_dataRow["field"] = SqlString.Null;
>
>_dataRow is of type DataRow and the associated field is of type varchar.
>
>after saving this change, the column in my database has value "Null"
>instead of the 'real' NULL!
>
>you could then get the row by executing
>
>SELECT * FROM mytable WHERE field = 'Null'
>
>and not by
>
>SELECT * FROM mytable WHERE field IS NULL
>
>isn't that strange?
>
>
>table:
>create table DBTEST (timecode datetime, strfield varchar(100))
>where column timecode is defined as primary key.
>
>this is my testapp:
>using System;
>using System.Data;
>using System.Data.SqlClient;
>using System.Data.SqlTypes;
>
>namespace DBProblem
>{
> public class DBProblem
> {
> public static int Main(string[] args)
> {
> // DB connection
> SqlConnection Connection = new SqlConnection("Server
>=;Database=;User ID=;Password=;Application Name=dbproblem");
> Connection.Open();
>
> // Dataset bef�llen
> SqlCommand Command = new SqlCommand("insert into DBTEST
>(timecode, strfield) values (@timecode, @strfield)", Connection);
> Command.Parameters.Add(new SqlParameter("@timecode",
>SqlDbType.DateTime));
> Command.Parameters["@timecode"].Value = DateTime.Now;
> Command.Parameters.Add(new SqlParameter("@strfield",
>SqlDbType.VarChar));
> Command.Parameters["@strfield"].Value = SqlString.Null;
> Command.ExecuteNonQuery();
>
> // row was inserted with column strfield containing NULL
>
> Command = new SqlCommand("select * from DBTEST",
>Connection);
> SqlDataAdapter _DataAdapter = new SqlDataAdapter(Command);
> SqlCommandBuilder _CommandBuilder = new SqlCommandBuilder
>(_DataAdapter);
>
> DataSet _DataSet = new DataSet();
>
> _DataAdapter.Fill(_DataSet, "DBTEST");
>
> DataRow _DataRow = _DataSet.Tables["DBTEST"].Rows[0];
> _DataRow["strfield"] = SqlString.Null;
> _DataAdapter.Update(_DataSet, "DBTEST");
>
> // now, column strfield of first row contains "Null"
>
> Connection.Close();
>
> return 0;
> }
> }
>}
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