Question

I have a ‘search’ textbox. When a user enters a text, I want to automatically fill dataGridView. But txtSearch.Text always shows “”. How do I solve this?

If there is no text in txtSearch, dataGridView must shows all data.

This is the code:

private void txtSearch_TextChanged(object sender, EventArgs e)
{
    //grid.Rows.Clear();
    OleDbDataReader dr = default(OleDbDataReader);
    using (OleDbConnection cn = new OleDbConnection(
               "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" 
               + Application.StartupPath + "\\MyAcsessDb.accdb"))
    {
        cn.Open();
        OleDbCommand cmd = new OleDbCommand(
            "Select * FROM Student WHERE [Name] Like '%@Name%' ", cn);

        cmd.Parameters.Add("@Name", OleDbType.Char).Value = txtSearch.Text;

        dr = cmd.ExecuteReader();

        if (dr.HasRows == true)
        {
            while (dr.Read())
            {
                grid.Rows.Add(dr[0].ToString(), 
                              dr[1].ToString(), 
                              dr[2].ToString(), 
                              dr[3].ToString());
            }
        }
        else
        {
            MessageBox.Show("No Data!");
        }
    }
}

Answer 1

Put jolly characters outside parameter:

cmd.Parameters.Add("@Name", OleDbType.Char).Value = "%" + txtSearch.Text + "%";