两次查询之间似乎无法正常工作

Question

This doesn't seem to work well any help

this.con.Open();
string selectCommandText = "Select * from paymentrecord where Payment_date >= " + dateTimePicker2.Value.ToString("dd-MM-yyyy") + " and  Payment_date <" + dateTimePicker1.Value.ToString("dd-MM-yyyy") + "";
OleDbDataAdapter adapter = new     OleDbDataAdapter(selectCommandText, this.con);
OleDbCommandBuilder builder = new OleDbCommandBuilder(adapter);
DataTable dataTable = new DataTable();
adapter.Fill(dataTable);
this.dataGridView1.DataSource = dataTable;
this.con.Close();

this one also doesn't seem to work well. it gives me records from different dates, sometimes too i don't get any records while they are records with the date i selected

this.con.Open();
        string selectCommandText = "Select * from paymentrecord where Payment_date  BETWEEN " + dateTimePicker2.Value.ToString("dd-MM-yyyy") +" and "+ dateTimePicker1.Value.ToString("dd-MM-yyyy") + "";
        OleDbDataAdapter adapter = new OleDbDataAdapter(selectCommandText, this.con);
        OleDbCommandBuilder builder = new OleDbCommandBuilder(adapter);
        DataTable dataTable = new DataTable();
        adapter.Fill(dataTable);
        this.dataGridView1.DataSource = dataTable;
        this.con.Close();

Answer 1

Did your query give u the correct result?

I think Payment_date is a string. String comparison doesn't give u correct result. It should be DateTime instead.

The operator greater than or lesser than will compare the values of the paymentDate in string. So it gives u wierd result.