I keep getting the error System.Data.SqlClient.SqlException: 'Incorrect syntax near '#'.'

Question

Hi please help I keep getting the error System.Data.SqlClient.SqlException: 'Incorrect syntax near '#'.' below is the code Thanks

private void AddBirthDayToCal(int startDayAtFlNumber)
        {
            var startDate = new DateTime(currentDate.Year, currentDate.Month, 1);
            var endDate = startDate.AddMonths(1).AddDays(-1);
            SqlConnection FamilyMembersConnection;
            FamilyMembersConnection = new SqlConnection("Data Source =.\\SQLEXPRESS; AttachDbFilename = " + Application.StartupPath + "\\MyFamily.mdf; Integrated Security = True; Connect                         Timeout = 30; User Instance = True");
            FamilyMembersConnection.Open();
            FamilyMembersCommand = new SqlCommand($"select * from FamilyMembers where Birthday between #{startDate.ToShortDateString()}# and #{endDate.ToShortDateString()}#", FamilyMembersConnection);
            FamilyMembersAdapter = new SqlDataAdapter();
            FamilyMembersAdapter.SelectCommand = FamilyMembersCommand;
            FamilyMembersTable = new DataTable();
            FamilyMembersAdapter.Fill(FamilyMembersTable);
            foreach (DataRow row in FamilyMembersTable.Rows)
            {
                var BirthDay = DateTime.Parse(Conversions.ToString(row["BirthDay"]));
                var link = new LinkLabel();
                link.Tag = row["FamilyMembersID"];
                link.Name = $"link{row["FamilyMembersID"]}";
                link.Text = Conversions.ToString(row["First_Name"]);
                listFlDay[BirthDay.Day - 1 + (startDayAtFlNumber - 1)].Controls.Add(link);
            }
        }

Answer 1

It's because you put '#' in the query

FamilyMembersCommand = new SqlCommand($"select * from FamilyMembers where Birthday between #{startDate.ToShortDateString()}# and #{endDate.ToShortDateString()}#", FamilyMembersConnection);

Change it to be like this

FamilyMembersCommand = new SqlCommand($"select * from FamilyMembers where Birthday between '{startDate.ToShortDateString()}' and '{endDate.ToShortDateString()}'", FamilyMembersConnection);

Answer 2

The # in sql allows you to reference a temporary object or procedure within the current session. That being said, you shouldn't need any # in the query. I'm assuming you'll want to replace those with single quotes as the string interpolation you are doing should resolve the properties you are passing in.