在SQL Server数据库上执行简单查询时没有错误或结果

Question

This is my first approach to SQL Server. I have exported my Access DB to SQL Server and want to use it in my application. I have added the new SQL DB to my C# project and replaced OleDB with Sql . I am now unable to execute queries which where perfectly working with local DB in Access.

Query:

string query = @"SELECT SessionID, SemesterA, SemesterB, RoomID, SessionDate, SessionTimeStart, SessionTimeEnd" +
               " FROM [Session] " +
               " WHERE RoomID = @RoomID " +
               " AND SessionDate = getdate() ";

I have replaced Date() with getdate() as instructed by the VS error, but the query does not produce any result (should return one record, Access DB does)

My RoomSelect form code:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace AutoReg
{
    public partial class RoomSelect : Form
    {

        DataTable queryResult = new DataTable();
        public string RoomID;
        RoomActiveSession RoomActiveSessionForm = new RoomActiveSession();

        public RoomSelect()
        {
            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)
        {

            switch (listBox1.SelectedItem.ToString())
            {
                case "MB0302":
                    RoomID = listBox1.SelectedItem.ToString();
                    roomQuery();
                    break;

                case "MC1001":
                    RoomID = listBox1.SelectedItem.ToString();
                    roomQuery();
                    break;

                case "MC3203":
                    RoomID = listBox1.SelectedItem.ToString(); 
                    roomQuery();
                    break;

                case "MC3204":
                    RoomID = listBox1.SelectedItem.ToString();
                    roomQuery();
                    break;

            }
        }

        public void roomQuery()
        {
            string ConnStr = "Data Source=DUZY;Initial Catalog=AutoRegSQL;Integrated Security=True";

            SqlConnection MyConn = new SqlConnection(ConnStr);
            MyConn.Open();

            //SQL query that todays sessions for the given roomID
            string query = @"SELECT SessionID, SemesterA, SemesterB, RoomID, SessionDate, SessionTimeStart, SessionTimeEnd" +
               " FROM [Session] " +
               " WHERE RoomID = @RoomID " +
               " AND SessionDate = getdate() ";

            SqlCommand command = new SqlCommand(query, MyConn);

            command.Parameters.Add("RoomID", SqlDbType.Char).Value = RoomID;


            SqlDataAdapter adapter = new SqlDataAdapter(command);

            adapter.Fill(queryResult);

            if (queryResult.Rows.Count == 0)
            {
                MessageBox.Show("No active sessions today for the given room number");
                MyConn.Close();
            }
            else
            {

                RoomActiveSessionForm.SetDataSouce(queryResult);

                this.Hide();
                RoomActiveSessionForm.ShowDialog();

                MyConn.Close();
            }


        }

    }
}

When I run the program, I receive a message "No active sessions today for the given room number" which should be executed when there are no results to the query, but I know for a fact, that it should return one record)

Answer 1

The function getdate() actually returns a datetime . Try converting it to a date:

AND SessionDate = cast(getdate() as date)

The time component is probably the problem -- preventing a match between the date and the datetime.