OleDb query with positioned parameter

mel C

Hi,

I'm a newbie in C#, I wrote an OLEDb query with positioned parameter. It seems not working. Can anyone please point out where I've done wrong? Thanks in advance.

Here is my code:

using (OleDbConnection conn = new OleDbConnection(connString))

{

String key = textbox1.text;

string cmd = "Select * from [" + filename + "] Where " + fieldname + " like ?";

OleDbCommand command= new OleDbCommand(cmd, conn);

OleDbParameter parameter = new OleDbParameter("@key",OleDbType.VarChar,30);

parameter.Value = "'%"+key+"%'";

command.Parameters.Add(parameter);

conn.Open();

OleDbDataAdapter dataAdapter = new OleDbDataAdapter(cmd, conn);

OleDbCommandBuilder commandBuilder = new OleDbCommandBuilder(dataAdapter);

DataTable table = new DataTable();

table.Locale = System.Globalization.CultureInfo.InvariantCulture;

dataAdapter.Fill(table);

}

3 Replies

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Jan Montano17y ago
when you browse the command statement during debug, you'll always see the ? and it will not be replaced. It just replaces the ? with the appropriate parameter during execution.

instead of using dataadapter use this:

OleDbDataReader reader = command.ExecuteReader();    while(reader.Read()){
       MessageBox.Show("test");
   }         reader.Close();    con.Close();
---------
during debug, does it actually enter the reader.Read() block?
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mel C17y ago
Hi Jan,

Thanks for the suggestion. I tried, but it's still the same.

The parameter didn't add on to the '?' in cmd statement.

the cmd statement output is still "Select * from [ABC.csv] Where fieldname like ?"

instead of "Select * from [ABC.csv] Where fieldname like '%key%'"

I tried command.Parameters.AddWithValue("?", "'%" + key + "%'"), also not working.
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Jan Montano17y ago
I'm not sure if this will do any good but try to replace
OleDbParameter parameter = new OleDbParameter("@key",OleDbType.VarChar,30);
with
OleDbParameter parameter = new OleDbParameter();

with
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