我试图将null datetime值插入到数据库中，但是它给了我数据类型在条件表达式中不匹配。这个问题是根据我的观察，当我试图插入null日期来访问数据库时我改成了代码，但仍然没有解决错误
string bank = txtbankname.Text;
bank = "";
string cheque = txtchequeno.Text;
cheque = "";
string billno = txtbillno.Text;
billno = "";
string codecreate = txtcodecreator.Text;
codecreate = "";
string connetionString = null;
connetionString = ConfigurationManager.ConnectionStrings["AccessConnectionString"].ConnectionString;
cnn.ConnectionString = connetionString;
string SqlString = "Insert Into Billing([FormNo],[Date],[TruckNo],[Office_Code],[Party_Code],[Party_Code1],[Location],[Supplier],[Item],[Invoice_no],[Invoice_date],[Package],[Weight],[Invest_Amount],[Percentage],[Amount],[Total_Amount],[Payment_Amount],[Payment_Type],[Bank_Name],[Cheque_No],[Cheque_Date],[Bill_No],[Bill_Date],[Code_Create]) Values (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)";
using (cmd = new OleDbCommand(SqlString, cnn))
{
cnn.Open();
cmd.CommandType = CommandType.Text;
cmd.Parameters.AddWithValue("@FormNo", txtformno.Text);
cmd.Parameters.AddWithValue("@Date", txtdate.Text);
cmd.Parameters.AddWithValue("@TruckNo", txttruck.Text);
cmd.Parameters.AddWithValue("@Office_Code", txtofficecode.Text);
cmd.Parameters.AddWithValue("@Party_Code", txtpartycode.Text);
cmd.Parameters.AddWithValue("@Party_Code1", txtpartycode1.Text);
cmd.Parameters.AddWithValue("@Location", txtlocation.Text);
cmd.Parameters.AddWithValue("@Supplier", txtsupplier.Text);
cmd.Parameters.AddWithValue("@Item", txtitem.Text);
cmd.Parameters.AddWithValue("@Invoice_no", txtinvoice.Text);
cmd.Parameters.AddWithValue("@Invoice_date", DateTime.Parse(txtmaskinvoice.Text));
cmd.Parameters.AddWithValue("@Package", txtpackage.Text);
cmd.Parameters.AddWithValue("@Weight", txtwieght.Text);
cmd.Parameters.AddWithValue("@Invest_Amount", Convert.ToDouble(txtinvestamount.Text));
cmd.Parameters.AddWithValue("@Percentage", txtpercentage.Text);
cmd.Parameters.AddWithValue("@Amount", Convert.ToDouble(txtamount.Text));
cmd.Parameters.AddWithValue("@Total_Amount", Convert.ToDouble(txttotalamount.Text));
cmd.Parameters.AddWithValue("@Payment_Amount", Convert.ToDouble(txtpaymentamount.Text));
cmd.Parameters.AddWithValue("@Payment_Type", txtpaymenttype.Text);
if (txtbankname.Text == "")
{
cmd.Parameters.AddWithValue("@Bank_Name", bank);
}
else
{
cmd.Parameters.AddWithValue("@Bank_Name", txtbankname.Text);
}
if (txtchequeno.Text == "")
{
cmd.Parameters.AddWithValue("@Cheque_No", cheque);
}
else
{
cmd.Parameters.AddWithValue("@Cheque_No", txtchequeno.Text);
}
DateTime chequeDate;
if (DateTime.TryParse(txtmaskchequedate.Text, out chequeDate))
{
cmd.Parameters.AddWithValue("@Cheque_Date", chequeDate);
}
else
{
// cmd.Parameters.AddWithValue("@Cheque_Date", DateTime.TryParse(txtmaskchequedate.Text,out value1));
cmd.Parameters.AddWithValue("@Cheque_Date", DBNull.Value);
}
if (txtbillno.Text == "")
{
cmd.Parameters.AddWithValue("@Bill_No", billno);
}
else
{
cmd.Parameters.AddWithValue("@Bill_No", txtbillno.Text);
}
DateTime BillDate;
if (DateTime.TryParse(txtmaskbilldate.Text, out BillDate))
{
cmd.Parameters.AddWithValue("@Bill_Date", BillDate);
}
else
{
cmd.Parameters.AddWithValue("@Bill_Date", DBNull.Value);
}
if (txtcodecreator.Text == "")
{
cmd.Parameters.AddWithValue("@Code_Create", codecreate);
}
else
{
cmd.Parameters.AddWithValue("@Code_Create", txtcodecreator.Text.ToString());
}
int n = cmd.ExecuteNonQuery();
cnn.Close();
if (n > 0)
{
MessageBox.Show("Data Inserted Successfully", "Data Inserted ", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}