每当我在文本框中输入任何内容或空值时,都会出现错误。我的代码是这样的:
SqlCommand cmd = con.CreateCommand();
cmd.CommandText = "INSERT INTO Records
([Student ID], [First Name], [Last Name], [Middle Initial],
Gender, Address, Status, Year, Email, Course,
[Contact Number])
VALUES (@StudentID, @FirstName, @LastName , @MiddleInitial,
@Gender, @Address, @Status, @Year, @Email, @Course,
@ContactNumber)";
SqlParameter p1 = new SqlParameter("@StudentID", SqlDbType.NChar);
p1.Value = textBox1.Text;
cmd.Parameters.Add(p1);
SqlParameter p2 = new SqlParameter("@FirstName", SqlDbType.NVarChar);
p2.Value = textBox2.Text;
cmd.Parameters.Add(p2);
SqlParameter p3 = new SqlParameter("@LastName", SqlDbType.NVarChar);
p3.Value = textBox3.Text;
cmd.Parameters.Add(p3);
SqlParameter p4 = new SqlParameter("@MiddleInitial", SqlDbType.NChar);
p4.Value = comboBox1.Text;
cmd.Parameters.Add(p4);
SqlParameter p5 = new SqlParameter("@Gender", SqlDbType.NChar);
p5.Value = comboBox2.Text;
cmd.Parameters.Add(p5);
SqlParameter p6 = new SqlParameter("@Address", SqlDbType.VarChar);
p6.Value = textBox4.Text;
cmd.Parameters.Add(p6);
SqlParameter p7 = new SqlParameter("@Status", SqlDbType.NChar);
p7.Value = comboBox3.Text;
cmd.Parameters.Add(p7);
SqlParameter p8 = new SqlParameter("@Year", SqlDbType.VarChar);
p8.Value = comboBox4.Text;
cmd.Parameters.Add(p8);
SqlParameter p9 = new SqlParameter("@Email", SqlDbType.VarChar);
p9.Value = textBox5.Text;
cmd.Parameters.Add(p9);
SqlParameter p10 = new SqlParameter("@Course", SqlDbType.VarChar);
p10.Value = comboBox5.Text;
cmd.Parameters.Add(p10);
SqlParameter p11 = new SqlParameter("@ContactNumber", SqlDbType.VarChar);
p11.Value = textBox6.Text;
cmd.Parameters.Add(p11);
textBox1.Text = "";
textBox2.Text = "";
textBox3.Text = "";
textBox4.Text = "";
textBox5.Text = "";
textBox6.Text = "";
comboBox1.Text = "";
comboBox2.Text = "";
comboBox3.Text = "";
comboBox4.Text = "";
comboBox5.Text = "";
if (cmd.Parameters.Contains(System.DBNull.Value))
{
MessageBox.Show("Please complete the fields", "Information...",
MessageBoxButtons.OK, MessageBoxIcon.Warning,
MessageBoxDefaultButton.Button1);
}
else
{
MessageBox.Show("Data Inserted!", "Information ... ",
MessageBoxButtons.OK, MessageBoxIcon.Information,
MessageBoxDefaultButton.Button1);
}
cmd.ExecuteNonQuery();
con.Close();
错误是:
if(cmd.Parameters.Contains(System.DBNull.Value))
我正在使用 SQL Server 和 C#。