C＃使用一个文本框过滤具有多行的搜索数据表

Question

I have created a filter search for my attendance monitoring system , it searches by the employee name but not with other fields, I think I'm gonna use the LIKE keyword but I don't know how to do it. Here's my code

private void textBox1_TextChanged(object sender, EventArgs e)
{ 
    connection.Open();
    OleDbCommand command = new OleDbCommand();
    command.Connection = connection;
    string query = "SELECT * FROM tblEmployee WHERE [Firstname] like @1";
    command.parameters.AddWithValue("@1",textBox1.Text);
    command.CommandText = query;
    OleDbDataAdapter da = new OleDbDataAdapter(command);
    DataTable dt = new DataTable();
    da.Fill(dt);
    dataGridView1.DataSource = dt;
    dataGridView1.Update();
    dataGridView1.Refresh();
    connection.Close(); 
}

Answer 1

The behaviour matches exactly with the query you wrote, you should rewrite the query to match your requirements:

string query = "SELECT * FROM tblEmployee WHERE [Firstname] like '%' + @1 + '%' OR [OtherColumn] LIKE '%' + @1 + '%'";

BTW, I have changed slightly your LIKE to make it behave like a 'it does contain XXX'.