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cmd.Parameters.Add  parameter always required?

Posted on 2008-10-14
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Last Modified: 2013-12-17
I'm inserting a record in a MS-access database.   I'm doing it in the c# section of an asp.net site

I use this code:

cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = ((TextBox)(FormView1.FindControl("txtMyndaTexti"))).Text;

The thing is that the column isn't required in the database  but the c#-code requires it,   so if the txtMyndatexti is empty I get an error   "No value given for one or more required parameters"
but the txtMyndatexti  has to be able to be empty

Is that not possible when we use this code?

cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = ((TextBox)(FormView1.FindControl("txtMyndaTexti"))).Text;

I used befor another method where I put :

dbRow["Myndatexti"] = ((TextBox)(FormView1.FindControl("txtMyndaTexti"))).Text;

and that works just fine whether  the textbox is empty or not.  

For some other reasons I needed to change the code and use the prior one cmd.Parameter.add(.....)
which has these rather boring sideeffects.

Does anyone know how to handle this?

string strConn = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source="+GetConnectionString();
 
         string strSQL = "INSERT into Frettir (CreatedBy,CreatedOn,Title,Description,Starts,Ends,CatId,SectionId,ArticleExt,Myndatexti,MyndUrAlbumi,NrMyndar) values(?,?,?,?,?,?,?,?,?,?,?,?)";
         OleDbConnection conn = new OleDbConnection(strConn); 
         conn.Open();
 
         OleDbCommand cmd = new OleDbCommand();
 
         cmd = new OleDbCommand(strSQL,conn );
 
         cmd.Parameters.Add("@CreatedBy",OleDbType.Integer).Value = notandi;
        cmd.Parameters.Add("@CreatedOn",OleDbType.Date, 50).Value = DateTime.Now;
          cmd.Parameters.Add("@Title",OleDbType.Char, 50).Value = ((TextBox)(FormView1.FindControl("TitleTextBox"))).Text.ToString();
        cmd.Parameters.Add("@Description",OleDbType.Char, 50).Value = ((RadEditor)(FormView1.FindControl("ContentTextBox"))).Html;
         cmd.Parameters.Add("@Starts",OleDbType.Date).Value = dstartdate;
            cmd.Parameters.Add("@Ends",OleDbType.Date).Value = finaldate;
          cmd.Parameters.Add("@CatId",OleDbType.Integer).Value = Convert.ToInt32(((DropDownList)(FormView1.FindControl("DropDownList3"))).SelectedValue); 
          cmd.Parameters.Add("@SectionId",OleDbType.Integer).Value = 1;
 
        string ext = Uploader.NewsPictures.UploadExtension(this);
        if (ext.Length > 0)
        {
            ((TextBox)(FormView1.FindControl("TextBox4"))).Text = ext;
        }
 
        if (((TextBox)(FormView1.FindControl("TextBox4"))).Text != "" & ((TextBox)(FormView1.FindControl("TextBox4"))).Text != "0")
        {
            cmd.Parameters.Add("@ArticleExt",OleDbType.Char, 50).Value = ((TextBox)(FormView1.FindControl("TextBox4"))).Text.ToString();
            
 
        }
       
        cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = ((TextBox)(FormView1.FindControl("txtMyndaTexti"))).Text;
        cmd.Parameters.Add("@MyndUrAlbumi",OleDbType.Boolean).Value = ((CheckBox)(FormView1.FindControl("ChkBoxMyndUrAlbumi"))).Checked;
        //dbRow["Myndatexti"] = ((TextBox)(FormView1.FindControl("txtMyndaTexti"))).Text;
        //dbRow["MyndUrAlbumi"] = ((CheckBox)(FormView1.FindControl("ChkBoxMyndUrAlbumi"))).Checked;
        if ( ((TextBox)(FormView1.FindControl("TextBox1"))).Text == "")
        {
            ((TextBox)(FormView1.FindControl("TextBox1"))).Text = "0";
            
        }
        
        cmd.Parameters.Add("@NrMyndar",OleDbType.Integer).Value = Convert.ToInt32(((TextBox)(FormView1.FindControl("TextBox1"))).Text);
        //dbRow["NrMyndar"] = Convert.ToInt32(((TextBox)(FormView1.FindControl("TextBox1"))).Text);
 
    
 
 
 
        
         cmd.ExecuteNonQuery();

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Question by:bjorkn
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6 Comments
 
LVL 53

Expert Comment

by:Dhaest
ID: 22718360
Did you check this:
if ((TextBox)(FormView1.FindControl("TextBox4"))).Text  = "" then
   cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = dbNull;
else
cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = ((TextBox)(FormView1.FindControl("txtMyndaTexti"))).Text;
end if
0
 

Author Comment

by:bjorkn
ID: 22723606
Yes I know this works but I would have liked to have it in one line instead of repeating the code.  Like this it can cause errors in maintenance.  that is you change it in one place and forget the other.

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LVL 53

Expert Comment

by:Dhaest
ID: 22728431
It won't be possible, because your stored procedure always expects a number of parameters. When you don't pass them all, you'll get an error from your database.
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Author Comment

by:bjorkn
ID: 22729683
It turns out that the dbNull isn't accepted in the line:

cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = dbNull;

I get this error

Error      1      'System.DBNull' is a 'type' but is used like a 'variable'      

Any ideas?
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LVL 53

Accepted Solution

by:
Dhaest earned 250 total points
ID: 22729726
cmd.Parameters.Add("@Myndatexti",OleDbType.Char, 50).Value = DBNull.Value;
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Author Closing Comment

by:bjorkn
ID: 31505994
Not exactly what I was looking for but solved the problem so far
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