c# - SqlParameterCollection 只接受非空的 SqlParamter 类型对象，不接受 String 对象

Question

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 ( @Student ID,  @First Name, @Last Name, " + 
                  "@Middle Initial, @Gender, @Address, @Status, @Year, @Email, " + 
                  "@Course, @Contact Number)";

        SqlParameter p1 = new SqlParameter("@[Student ID]", SqlDbType.Int);
        p1.Value = textBox1.Text;
        cmd.Parameters.Add("1");
        SqlParameter p2 = new SqlParameter("@First Name", SqlDbType.VarChar);
        p2.Value = textBox2.Text;
        cmd.Parameters.Add("p2");
        SqlParameter p3 = new SqlParameter("@Last Name", SqlDbType.NVarChar);
        p3.Value = textBox3.Text;
        cmd.Parameters.Add("p3");
        SqlParameter p4 = new SqlParameter("@Middle Initial", 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("9");
        SqlParameter p10 = new SqlParameter("@Course", SqlDbType.VarChar);
        p10.Value = comboBox5.Text;
        cmd.Parameters.Add("p10");
        SqlParameter p11 = new SqlParameter("@Contact Number", SqlDbType.VarChar);
        p11.Value = textBox6.Text;
        cmd.Parameters.Add("p11");

        cmd.ExecuteNonQuery();
        con.Close();

Answer 1

将参数的实例添加到集合中，而不是字符串“p11”

    SqlParameter p11 = new SqlParameter("@ContactNumber", SqlDbType.VarChar);
    p11.Value = textBox6.Text;
    cmd.Parameters.Add(p11);

而且您不需要在参数名称中使用空格来让您的生活变得困难。

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)";

.....

// Name your parameters without spaces
SqlParameter p1 = new SqlParameter("@StudentID", SqlDbType.Int);
p1.Value = textBox1.Text;
cmd.Parameters.Add(p1);
.....

命令文本中的参数占位符将替换为同名参数的值，无需在参数占位符内添加空格使事情变得复杂。