[当我在C＃中提交表单时程序崩溃

Question

每当我在C＃应用程序中单击表单的提交按钮时，它就会崩溃。该程序假设将所有数据带到在Microsoft SQL Server中制成的我的数据库中下面是代码

string connection = "Data Source=DESKTOP-EON545D;Initial Catalog=TMS_Database;Integrated Security=True";
public LoginFrame()
        {

            InitializeComponent();
            con = new SqlConnection(connection);

        }


 private void button2_Click(object sender, EventArgs e)
    {
        if (checkBox1.Checked)//if terms and conditions are accepted
        {
            AddNewTenant();


        }
    }

public void AddNewTenant()
        {
            string username = textBox1.Text.ToString();
            string password = textBox2.Text.ToString();
            string email = textBox7.Text.ToString();
            string firstName = textBox5.Text.ToString();
            string lastName = textBox6.Text.ToString();
            string address = richTextBox1.Text.ToString();
            int phone = int.Parse(textBox8.Text.ToString());
            string CNIC = textBox9.Text.ToString();
            string appartmentType = radioButton1.Text.ToString();

            string sqlStatement = "INSERT INTO tenant(username,password,firstname,lastname,email,current_address,phone,appartmentType)values" + "'" + username + "'," + "'" + password + "'," + "'" + firstName + "'," + "'" + lastName + "'," + "'" + email + "'," + "'" + address + "'," + "'" + phone + "'," + "'" + appartmentType + "')";
            //Console.WriteLine(sqlStatement);
            SqlCommand cmd = new SqlCommand(sqlStatement, con);
            con.Open();
            int rowsinsert = cmd.ExecuteNonQuery();
            con.Close();
        }

这是我得到的错误

Answer 1

您的SQL查询字符串在“值”附近有问题。

string sqlStatement = "INSERT INTO 

tenant(username, password, firstname, lastname, email, current_address, phone, 
appartmentType) values(" + "'" + username + "'," + "'" + password + "'," + "'" + 
firstName + "'," + "'" + lastName + "'," + "'" + email + "'," + "'" + address + "'," + 
"'" + phone + "'," + "'" + appartmentType + "')";

您在值后错过了'（'。并且我建议使用以下语法

string sqlStatement =“插入到

承租人（用户名，密码，名字，姓氏，电子邮件，当前地址，电话，公寓类型）值（@用户名，@密码，@名字，@姓，@电子邮件，@地址，@电话，@appartmentType）“;

SQLiteCommand command = new SQLiteCommand(con)
command.Text = sqlStatement;
command.CommandType = SQLiteCommandType
command.CommandType = CommandType.Text;
command.Parameters.Add(new SQLiteParameter("@username", username));
command.Parameters.Add(new SQLiteParameter("@password", password));
command.Parameters.Add(new SQLiteParameter("@firstname", firstname));
command.Parameters.Add(new SQLiteParameter("@lastname", lastname));
command.Parameters.Add(new SQLiteParameter("@email", email));
command.Parameters.Add(new SQLiteParameter("@current_address", current_address));
command.Parameters.Add(new SQLiteParameter("@phone", phone));
command.Parameters.Add(new SQLiteParameter("@appartmentType", appartmentType));

command.ExecuteNoneQuery();