[IWE] C# ODBCReader questions

[Christian Conrad]

Guys,

So what you're saying, Critter, is that the Table object has a property Columns which is an array of objects of type DataColumn, and that each such element in turn has a property ColumnName?

Two questions occur: Critter, wouldn't it almost have been quicker to type that, than finding and pasting that example? ;-) And Barry, don't you have *any* bloody documentation that says the same thing?

Note that I'm not necessarily blaming you, Barry; for all I know, your C# docs really might suck so badly. Had you been using Delphi, selecting your Table [Query, DataSet, whatever] object and pressing F1 for help would have told you exactly that.

The things you poor suc^H^H^Husers of lesser environments have to put up with...


A- and be-musedly,

  Sir Cyclic


Chris Rathman <Chris.Rathman@tx.rr.com> wrote: 
> Don't have time to explain, but here's code that should have the effect 
> you want (see the iterate over columns):
> 
>             System.Data.SqlClient.SqlConnection Db;
>             System.Data.SqlClient.SqlDataAdapter Da;
>             System.Data.DataSet Ds;
>             System.Data.DataTable Dt;
>             System.Data.SqlClient.SqlCommand Cmd;
>             System.Data.SqlClient.SqlDataReader Rs;
> 
>             string connectionStr = "Server=.; Database=NorthWind; 
> Integrated Security=sspi";
>             string commandStr;
> 
>             // open up a database connection
>             Db = new System.Data.SqlClient.SqlConnection(connectionStr);
>             Db.Open();
> 
>             // create a table
>             commandStr = "CREATE TABLE TestCSharp(" +
>                          "   TestCD      CHAR(2)     NOT NULL PRIMARY 
> KEY," +
>                          "   Description VARCHAR(80) NOT NULL)";
>             Cmd = new System.Data.SqlClient.SqlCommand(commandStr, Db);
>             Cmd.CommandType = System.Data.CommandType.Text;
>             Rs = Cmd.ExecuteReader();
>             Rs.Close();
> 
>             // example using DataAdapter (sans SqlConnection)
>             commandStr = "SELECT * FROM TestCSharp";
>             Da = new System.Data.SqlClient.SqlDataAdapter(commandStr, 
> connectionStr);
>             Ds = new System.Data.DataSet();
>             Da.Fill(Ds, "Test");
>             Dt = Ds.Tables[0];
>             // iterate over the columns
>             foreach (System.Data.DataColumn col in Dt.Columns)
>             {
>                 string s = col.ColumnName;
>             }
>             // iterate over the rows
>             foreach (System.Data.DataRow row in Dt.Rows)
>             {
>                 System.Console.WriteLine(row["TestCD"] + " " + 
> row["Description"]);
>             }
> 
>             // drop the table
>             commandStr = "DROP TABLE TestCSharp";
>             Cmd = new System.Data.SqlClient.SqlCommand(commandStr, Db);
>             Cmd.CommandType = System.Data.CommandType.Text;
>             Rs = Cmd.ExecuteReader();
>             Rs.Close();
> 
>             // close the database connection
>             Db.Close();
> 
> 
> Chris.
> Barry Roomberg wrote:
> > On Friday 12 January 2007 11:52, Chris Rathman wrote:
> >   
> >> You access it either way.  Rs["Example"] or Rs[n].  Accessing by index
> >> is faster since it doesn't have to do a dictionary search.
> >>     
> >
> > You misunderstand.
> > I don't KNOW the field names at that point.
> > This is the result of a "select *".
> > And my goal is to assign them the a hash, by field name.
> > So, is there a way of getting the list of field names in it?
> >
> >   
> >> Chris.
> >>
> >> Barry Roomberg wrote:
> >>     
> >>> Since I can get the count of fields, and I can loop throught that, is
> >>> there any what, given a numeric index, to determine the name of the
> >>> field? This would enable generaric setup / assign code.
> >>>
> >>> On Friday 12 January 2007 11:43, Chris Rathman wrote:
> >>>       
> >>>> I've used OleDbDataReader and SqlDataReader in the past, but I'm not
> >>>> sure of the particular type for ODBC?  I put together some notes on C#
> >>>> that might be useful (see the section on databases):
> >>>>
> >>>>     http://www.angelfire.com/tx4/cus/notes/csharp-syntax.html
> >>>>
> >>>> In general, I could have something like:
> >>>>
> >>>>     ...  bunch of code to set up Command....
> >>>>
> >>>>     OleDbDataReader Rs = Cmd.ExecuteReader();
> >>>>     Rs.Read();
> >>>>     while (Rs.Read())
> >>>>     {
> >>>>         string example = (string)Rs["Example"];
> >>>>     }
> >>>>
> >>>> So, the answer is likely that you want to use the associative array that
> >>>> corresponds to the data reader object.
> >>>>
> >>>> Chris.
> >>>>
> >>>> Barry Roomberg wrote:
> >>>>         
> >>>>> If I do a "select *" in an ODBC connection, and then have the reader
> >>>>> pulling the data, how can I pull the assoicated field name from the
> >>>>> reader array? _______________________________________________
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