将C＃datetime发送到SQL Server-错误“从字符串转换日期和/或时间时转换失败”

Question

I am trying to submit a form that contains a few datetimepickers as well as other controls. other controls have no problem but when I take the datetimepicker date value and put it in a parameterised insert statement, this error happens:

Conversion failed when converting date and/or time from character string

I have tried the following methods:

1. custom datetime format:

    dateTimePicker1.Format = DateTimePickerFormat.Custom; dateTimePicker1.CustomFormat = "dd/MM/yyyy";' 

2. convert it to string and then into date time using datetime.parseexact, datetime.parse and Convert.ToDateTime.

3. tried this type of code as well:

    DateTime date2 = Convert.ToDateTime(dateTimePicker2.Text); 

Full code

con.Open();

string s = "insert into [NutritionClinicDatabase].[dbo].[PatientInformation] values(@NIC, @ClinicNo, @PatientCategory, @Date, @Name, @Gender, @DOB, @DateOfAdmission, @DateOfDischarge, @DurationOfVisit, @Age, @City, @Contact, @Height, @Weight, @UsualWweight, @ReferredUnit, @WC, @FatMass, @LeanBodyMass, @HandGripStrength, @Intake, @Illness, @Illness2, @Illness3, @Illness4, @Specify, @Other)";


cmd = new SqlCommand(s, con);
String strDateFormat = "yyyy-MM-dd";
cmd.Parameters.AddWithValue("@NIC", NIC);
cmd.Parameters.AddWithValue("@ClinicNo", ClinicNo);
cmd.Parameters.AddWithValue("@PatientCategory", PatientCategory);

if (PatientCategory == "Clinic Patient")
{
    cmd.Parameters.AddWithValue("@Date", SqlDbType.Date).Value = dateTimePicker1.Value.Date;
}
else if ((PatientCategory == "In-Ward Patient") || (PatientCategory == "ICU Patient"))
{
    cmd.Parameters.AddWithValue("@Date", DBNull.Value);
}

cmd.Parameters.AddWithValue("@Name", Name1);
cmd.Parameters.AddWithValue("@Gender", Gender);

//if (dateTimePicker2.CustomFormat == " ")
//    cmd.Parameters.AddWithValue("@DOB", DBNull.Value);
//else
cmd.Parameters.AddWithValue("@DOB", SqlDbType.Date).Value = dateTimePicker2.Value.Date;
// cmd.Parameters.AddWithValue("@DOB", SqlDbType.Date).Value = dateTimePicker2.Value.Date;

if ((PatientCategory == "In-Ward Patient") || (PatientCategory == "ICU Patient"))
{
    //if (dateTimePicker3.CustomFormat == " ")
    //    cmd.Parameters.AddWithValue("@DateOfAdmission", DBNull.Value);
    //else
    cmd.Parameters.AddWithValue("@DateOfAdmission", SqlDbType.Date).Value = dateTimePicker3.Value.Date;
    // cmd.Parameters.AddWithValue("@DOB", SqlDbType.Date).Value = dateTimePicker2.Value.Date;
    //if (dateTimePicker4.CustomFormat == " ")
    //    cmd.Parameters.AddWithValue("@DateOfDischarge", DBNull.Value);
    //else
    cmd.Parameters.AddWithValue("@DateOfDischarge", SqlDbType.Date).Value = dateTimePicker4.Value.Date;
    //cmd.Parameters.AddWithValue("@DateOfDischarge", DateTime.Parse(dateTimePicker4.Value.Date.ToString()));
    // cmd.Parameters.AddWithValue("@DOB", SqlDbType.Date).Value = dateTimePicker2.Value.Date;

    cmd.Parameters.AddWithValue("@DurationOfVisit", Duration);
}
else if (PatientCategory == "Clinic Patient")
{
    cmd.Parameters.AddWithValue("@DateOfAdmission", DBNull.Value);
    cmd.Parameters.AddWithValue("@DateOfDischarge", DBNull.Value);
    cmd.Parameters.AddWithValue("@DurationOfVisit", "Not Specified");
}

cmd.Parameters.AddWithValue("@Age", Age);
cmd.Parameters.AddWithValue("@City", City);
cmd.Parameters.AddWithValue("@Contact", Contact);
cmd.Parameters.AddWithValue("@Height", Height1);
cmd.Parameters.AddWithValue("@Weight", Weight);
cmd.Parameters.AddWithValue("@UsualWweight", UsualWeight);
//cmd.Parameters.AddWithValue("@CurrentWeight", CurrentWeight);
cmd.Parameters.AddWithValue("@ReferredUnit", ReferredUnit);
cmd.Parameters.AddWithValue("@WC", WC);
cmd.Parameters.AddWithValue("@FatMass", FatMass);
cmd.Parameters.AddWithValue("@LeanBodyMass", LeanBodyMass);
cmd.Parameters.AddWithValue("@HandGripStrength", HandGripStrength);
cmd.Parameters.AddWithValue("@Intake", Intake);
cmd.Parameters.AddWithValue("@Illness", Illness);
cmd.Parameters.AddWithValue("@Illness2", Illness2);
cmd.Parameters.AddWithValue("@Illness3", Illness3);
cmd.Parameters.AddWithValue("@Illness4", Illness4);
cmd.Parameters.AddWithValue("@Specify", Specify);
cmd.Parameters.AddWithValue("@Other", Other);

cmd.CommandType = CommandType.Text;
cmd.ExecuteNonQuery();

con.Close();

MessageBox.Show("Patient Registered");

Answer 1

You are not using AddWithValue correctly. The AddWithValue method takes a parameter name and an object that is the parameter value, not the type. I suggest you avoid AddWithValue entirely and instead use the Add method, such as:

cmd.Parameters.Add("@Date", SqlDbType.Date).Value = dateTimePicker1.Value.Date;