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ASP.NET 2.0 Basics If you are new to ASP or ASP.NET programming with version 2.0, this is the forum to begin asking questions. Please also see the Visual Web Developer 2005 forum.
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Old May 12th, 2006, 03:26 PM
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Default Database Queries

I am a coldfusion programmer moving to dotnet, and while I am not having a problem populating asp.net controls with data from my sql server. I can't figure out how to identify a data field value from the database in a conditional statement.
EG

If [table].[field] is X
then [do something]

I am sure it is simple, but I have been working on this for 2 days and can only get information on how to populate controls.

Thanks,

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Old May 13th, 2006, 03:46 AM
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Hi there,

Ca you show us some code? There's a big difference in how you should compare depending on where you use this code, and what data objects you are using (e.g. in the markup, in code behind with a dataset or a datareader and so on)

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Old May 13th, 2006, 11:27 AM
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In my example, I will keep the code in the codebehind. When the page loads, I would like to pull one record from the jobDetails table where the jobDetailsID is 1.
Lets say there is one bit field in the jobDetails table called requiresAddress

I would like to set the visibility of a form field based on the value of that bit field.
Here is what I have based on code from a wrox book.

if (!Page.IsPostBack )
        {
            SqlConnection MyConnection;
            SqlCommand MyCommand;
            DataTable MyDataTable;
            SqlDataReader MyReader;
            SqlParameter lobParam;

            MyConnection = new SqlConnection();
            MyConnection.ConnectionString =
        ConfigurationManager.ConnectionStrings["rdConnectionString"].ConnectionString;

            MyCommand = new SqlCommand();
            MyCommand.CommandText =
               " SELECT jobDetailsID, requiresAddress FROM jobDetails WHERE jobDetailsID = @jobDtailsID ";
            MyCommand.CommandType = CommandType.Text;
            MyCommand.Connection = MyConnection;

            lobParam = new SqlParameter();
            lobParam.ParameterName = "@jobDetailsID";
            lobParam.SqlDbType = SqlDbType.Int;
            lobParam.Size = 4;
            lobParam.Direction = ParameterDirection.Input;
            lobParam.Value = "1";

            MyCommand.Parameters.Add(lobParam);

            MyCommand.Connection.Open();
            MyReader = MyCommand.ExecuteReader(CommandBehavior.CloseConne ction);



            MyDataTable.Load(MyReader);
 // This is where I don't know what to do

            topinfo.Visible = MyDataTable.requiresAddress;

            MyDataTable.Dispose();
            MyCommand.Dispose();
            MyConnection.Dispose();

        }

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Old May 13th, 2006, 06:20 PM
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Hi frosty,

If all you need to do is check a single field, then you don't need the DataTable. Instead, you can read from the reader directly:

if (MyReader .Read())
{
  someControl.Visible = MyReader .GetBoolean(3);
}

where 3 is the (zero-based) index of the colum you want to read. If you want to improve the readability of the code, you can use GetOrdinal, that returns the index based on a name:

  someControl.Visible = MyReader.GetBoolean(MyReader.GetOrdinal("requiresA ddress"))

And if SomeColumn can be null in the database, you can check it before you try to get a boolean:

if (MyReader.IsDBNull(MyReader.GetOrdinal("requiresAd dress")))
{
  // value is null
}

Hope this helps,

Imar
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Imar Spaanjaars
Everyone is unique, except for me.
Author of ASP.NET 2.0 Instant Results and Beginning Dreamweaver MX / MX 2004
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