【发布时间】：2021-01-12 17:59:28
【问题描述】：
我正在制作一个测验应用程序，用户可以在其中编辑数据库中的问题。
我在下面的代码中尝试做的是，当用户打开 QuizEditForm 并在显示来自问题库的当前数据的 datagridview 中进行更改时，用户可以对其进行编辑，例如添加问题、删除、更新。
当用户进行更改时，我希望将其连同他的 UserID 重新插入到数据库中，这样如果多个用户使用该应用，他们就只能看到他们的问题。
但是，我不断收到许多我试图在我的 SQL 语句中修复的错误，例如声明标量变量、不正确的语法等。有没有人知道如何解决这个问题？
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Data.SqlClient;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace Quiz_Game_Official
{
public partial class QuizEditForm : Form
{
private string path = Path.Combine(System.IO.Directory.GetCurrentDirectory(), "Database1.mdf");
private string dbConnectionPath;
private SqlConnection connectionString;
private Form mParent;
public QuizEditForm(Form parent)
{
InitializeComponent();
int UserID = Program.UserID;
this.mParent = parent;
this.dbConnectionPath = String.Format(@"Data Source = (LocalDB)\MSSQLLocalDB; AttachDbFilename = {0}; Integrated Security = True", path);
this.connectionString = new SqlConnection(dbConnectionPath);
string SQL = "UPDATE QuestionBank SET UserID = "+UserID +
"SELECT UserID,QuestionID , QuestionText,CorrectAnswer,WrongAnswer1,WrongAnswer2,WrongAnswer3 FROM QuestionBank";
// string SQL = "SELECT UserID,QuestionID , QuestionText,CorrectAnswer,WrongAnswer1,WrongAnswer2,WrongAnswer3 FROM QuestionBank WHERE UserID =" +UserID ; // selecting questions
SqlDataAdapter sqlDataAdapter = new SqlDataAdapter(SQL, connectionString);
DataTable quizDataTable = new DataTable(); // prepare datatable to handle data for gridview
sqlDataAdapter.Fill(quizDataTable); // sqlDataAdapter respresents question Table
quizTable.DataSource = quizDataTable; // datatable is stil data , not UI representaion so we use this line to show it on the UI , this means table's datasource is quizDataTable variable
}
private void quizTable_CellValueChanged(object sender, DataGridViewCellEventArgs e) // one of the events , triggered when the user edits cell value
{
if (quizTable.CurrentRow != null)
{
this.connectionString = new SqlConnection(dbConnectionPath);
using (connectionString)
{
DataGridViewRow quizRow = quizTable.CurrentRow;// this line gets current editing table row
int UserID = Program.UserID;
string SQL = "DECLARE @QuestionBank TABLE (UserID INT)" +
"IF @QuestionID = 0 INSERT INTO QuestionBank(UserID,QuestionText, CorrectAnswer, WrongAnswer1, WrongAnswer2, WrongAnswer3) " +
"OUTPUT INSERTED.UserID INTO @QuestionBank(UserID) VALUES ("+UserID +")"+
"output INSERTED.QuestionID VALUES(@UserID,@QuestionText, @CorrectAnswer, @WrongAnswer1, @WrongAnswer2, @WrongAnswer3) ELSE " +
"UPDATE QuestionBank SET QuestionText = @QuestionText, CorrectAnswer = @CorrectAnswer, WrongAnswer1 = @WrongAnswer1, WrongAnswer2 = @WrongAnswer2, WrongAnswer3 = @WrongAnswer3 , UserID = @UserID " +
"output INSERTED.QuestionID WHERE QuestionID = @QuestionID"; //Question Add or Edit // update / insert
using (SqlCommand command = new SqlCommand(SQL, connectionString))
{
if (quizRow.Cells[0].Value == System.DBNull.Value) //the select row doesnt have question id meaning it is for new questions
{
command.Parameters.Add("@QuestionID", SqlDbType.Int).Value = 0; // we set question ID to 0 otherwise
}
else
{
command.Parameters.Add("@QuestionID", SqlDbType.Int).Value = quizRow.Cells[0].Value;
}
command.Parameters.Add("@QuestionText", SqlDbType.VarChar, 200).Value = quizRow.Cells[1].Value != System.DBNull.Value ? quizRow.Cells[1].Value : "";
command.Parameters.Add("@CorrectAnswer", SqlDbType.VarChar, 200).Value = quizRow.Cells[2].Value != System.DBNull.Value ? quizRow.Cells[2].Value : "";
command.Parameters.Add("@WrongAnswer1", SqlDbType.VarChar, 200).Value = quizRow.Cells[3].Value != System.DBNull.Value ? quizRow.Cells[3].Value : "";
command.Parameters.Add("@WrongAnswer2", SqlDbType.VarChar, 200).Value = quizRow.Cells[4].Value != System.DBNull.Value ? quizRow.Cells[4].Value : "";
command.Parameters.Add("@WrongAnswer3", SqlDbType.VarChar, 200).Value = quizRow.Cells[5].Value != System.DBNull.Value ? quizRow.Cells[5].Value : "";
try
{
this.connectionString.Open();
int result = (int)command.ExecuteScalar(); //when sql query is ran , it ouputs last inserted or updated id , get the id and store it to results variable
int modified = (int)result;
UserID = Program.UserID;
if (modified == 0)
{
MessageBox.Show("Quiz Table Update Failed");
}
quizTable.CurrentRow.Cells[0].Value = modified;
this.connectionString.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
}
}
}
private void quizTable_UserDeletingRow(object sender, DataGridViewRowCancelEventArgs e) // event triggered when user deletes a question
{
//e.Cancel = true;
if (quizTable.CurrentRow.Cells[0].Value != System.DBNull.Value)
{
if (MessageBox.Show("Are you sure to Delete this question?", "Warning", MessageBoxButtons.YesNo) == DialogResult.Yes) // user is asked if he is suere about deleting the question
{
this.connectionString = new SqlConnection(dbConnectionPath);
using (connectionString)
{
DataGridViewRow quizRow = quizTable.CurrentRow;
string SQL = "DELETE from QuestionBank WHERE QuestionID = @QuestionID"; //Question Add or Edit
using (SqlCommand command = new SqlCommand(SQL, connectionString))
{
command.Parameters.Add("@QuestionID", SqlDbType.Int).Value = quizRow.Cells[0].Value;
try
{
this.connectionString.Open();
int affectedRow = command.ExecuteNonQuery();
if (affectedRow == 0)
{
e.Cancel = true;
MessageBox.Show("Question delete failed");
}
this.connectionString.Close();
}
catch (Exception ex)
{
e.Cancel = true;
MessageBox.Show(ex.Message);
}
}
}
}
}
}
private void QuizEditForm_FormClosing(object sender, FormClosingEventArgs e)
{
this.mParent.Show();
}
}
}
【问题讨论】：
标签： c# sql sql-server-ce