iDB2Commands in Visual Studio 2010 - db2

Question

These are the basic things I know about iDB2Commands to be used in Visual Studio 2010. Could you please help me how could I extract data from DB2? I know INSERT, DELETE and Record Count. But SELECT or Extract Data and UPDATE I don't know.
Imports IBM.Data.DB2
Imports IBM.Data.DB2.iSeries
Public conn As New iDB2Connection
Public str As String = "Datasource=10.0.1.11;UserID=edith;password=edith;DefaultCollection=impexplib"
Dim cmdUpdate As New iDB2Command
Dim sqlUpdate As String
conn = New iDB2Connection(str)
conn.Open()
'*****Delete Records and working fine
sqlUpdate = "DELETE FROM expusers WHERE username<>#username"
cmdUpdate.Parameters.Add("username", iDB2DbType.iDB2Date)
cmdUpdate.Parameters("username").Value = ""
'*****Insert Records and working fine
sqlUpdate = "INSERT INTO expusers (username, password, fullname) VALUES (#username, #password, #fullname)"
cmdUpdate.Parameters.Add("username", iDB2DbType.iDB2VarChar)
cmdUpdate.Parameters.Add("password", iDB2DbType.iDB2VarChar)
cmdUpdate.Parameters.Add("fullname", iDB2DbType.iDB2VarChar)
cmdUpdate.Parameters("username").Value = txtUsername.Text
cmdUpdate.Parameters("password").Value = txtPassword.Text
cmdUpdate.Parameters("fullname").Value = "Editha D. Gacusana"
'*****Count Total Records and working fine
Dim sqlCount As String
Dim cmd As New iDB2Command
sqlCount = "SELECT COUNT(*) AS count FROM import"
cmd = New iDB2Command(Sql, conn)
Dim count As Integer
count = Convert.ToInt32(cmd.ExecuteScalar)
'*****Update Records and IT IS NOT WORKING AT ALL
sqlUpdate = "UPDATE expusers SET password = #password WHERE RECNO = #recno"
cmdUpdate.Parameters.Add("recno", iDB2DbType.iDB2Integer)
cmdUpdate.Parameters.Add("password", iDB2DbType.iDB2VarChar)
cmdUpdate.Parameters("recno").Value = 61
cmdUpdate.Parameters("password").Value = txtPassword.Text
cmdUpdate.Connection = conn
cmdUpdate.CommandText = sqlUpdate
cmdUpdate.ExecuteNonQuery()
conn.Close()
Please help me how to code the SELECT query wherein I could extract/fetch data from DB2 Database. Also, how could i update the records in the database.
Thanks!

Answer 1

Instead of ExecuteNonQuery(), look at ExecuteReader(). I don't have VS2010 installed, but try something like this:
iDB2Command cmdSelect = new iDB2Command("SELECT username, password, fullname FROM expusers", conn);
cmdSelect.CommandTimeout = 0;
iDB2DataAdapter da = new iDB2DataAdapter(cmdSelect);
DataSet ds = new DataSet();
da.Fill(ds, "item_master");
GridView1.DataSource = ds.Tables["expusers"];
GridView1.DataBind();
Session["TaskTable"] = ds.Tables["expusers"];
da.Dispose();
cmdSelect.Dispose();
cn.Close();
See: http://gugiaji.wordpress.com/2011/12/29/connect-asp-net-to-db2-udb-for-iseries/
If you aren't trying to bind to a grid, look at iDB2Command.ExecuteReader() and iDB2DataReader()

Answer 2

The DELETE is working fine? The code has the parameter type for "username" set to iDB2Date. The INSERT has "username" set to iDB2VarChar. How is the column defined in the table? Char, Varchar or Date?
On the UPDATE, you reference RECNO, but that does not seem to be a column in the table. Updating a relational database table by row number is a bad idea - the row numbers are not guaranteed to stay constant. If you are just testing, as I think you are, don't use RECNO, use RRN(). The DB2 for i syntax is WHERE rrn(expusers) = #recno
To help your testing, do a SELECT without a WHERE clause and list out all the rows. Make sure the name stored in the username column matches the name you are trying to update. Pay particular attention to the case of the data. If the name in expusers looks like "EDITHA D. GACUSANA", and #username is "Editha D. Gacusana" then it will not match on the WHERE clause.