使用C＃进行SQL插入查询

我现在遇到一个问题，我正在努力解决这个问题。 我只是尝试访问数据库并在C＃的帮助下插入一些值

我试过的东西（工作）

String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES ('abc', 'abc', 'abc', 'abc')"; 

插入了一个新行，一切正常，现在我尝试使用变量插入一行：

 String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id, @username, @password, @email)"; command.Parameters.AddWithValue("@id","abc") command.Parameters.AddWithValue("@username","abc") command.Parameters.AddWithValue("@password","abc") command.Parameters.AddWithValue("@email","abc") command.ExecuteNonQuery(); 

没有工作，没有插入任何值。 我又尝试了一件事

 command.Parameters.AddWithValue("@id", SqlDbType.NChar); command.Parameters["@id"].Value = "abc"; command.Parameters.AddWithValue("@username", SqlDbType.NChar); command.Parameters["@username"].Value = "abc"; command.Parameters.AddWithValue("@password", SqlDbType.NChar); command.Parameters["@password"].Value = "abc"; command.Parameters.AddWithValue("@email", SqlDbType.NChar); command.Parameters["@email"].Value = "abc"; command.ExecuteNonQuery(); 

愿有人能告诉我我做错了什么吗？

亲切的问候

编辑：

在另一行中，我正在创建一个新的SQL-Command

 var cmd = new SqlCommand(query, connection); 

仍然没有工作，我在上面的代码中找不到任何错误。

Answer 1

我假设您已连接到数据库，并且无法使用c＃执行插入参数。

您没有在查询中添加参数。 它应该看起来像：

 String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username,@password, @email)"; SqlCommand command = new SqlCommand(query, db.Connection); command.Parameters.Add("@id","abc"); command.Parameters.Add("@username","abc"); command.Parameters.Add("@password","abc"); command.Parameters.Add("@email","abc"); command.ExecuteNonQuery(); 

更新：

 using(SqlConnection connection = new SqlConnection(_connectionString)) { String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username,@password, @email)"; using(SqlCommand command = new SqlCommand(query, connection)) { command.Parameters.AddWithValue("@id", "abc"); command.Parameters.AddWithValue("@username", "abc"); command.Parameters.AddWithValue("@password", "abc"); command.Parameters.AddWithValue("@email", "abc"); connection.Open(); int result = command.ExecuteNonQuery(); // Check Error if(result < 0) Console.WriteLine("Error inserting data into Database!"); } } 

Answer 2

尝试

 String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username, @password, @email)"; using(SqlConnection connection = new SqlConnection(connectionString)) using(SqlCommand command = new SqlCommand(query, connection)) { //a shorter syntax to adding parameters command.Parameters.Add("@id", SqlDbType.NChar).Value = "abc"; command.Parameters.Add("@username", SqlDbType.NChar).Value = "abc"; //a longer syntax for adding parameters command.Parameters.Add("@password", SqlDbType.NChar).Value = "abc"; command.Parameters.Add("@email", SqlDbType.NChar).Value = "abc"; //make sure you open and close(after executing) the connection connection.Open(); command.ExecuteNonQuery(); connection.Close(); } 

Answer 3

最常见的错误（特别是在使用express时）“我的插入没有发生”是： 查找错误的文件 。

如果您使用的是基于文件的快速（而不是强附加），则项目文件夹中的文件（例如， c:\dev\myproject\mydb.mbd ） 不是程序中使用的文件。 构建时，会复制该文件 – 例如c:\dev\myproject\bin\debug\mydb.mbd ; 您的程序在c:\dev\myproject\bin\debug\的上下文中执行，因此您需要查看编辑是否实际发生。 检查是否确定：查询应用程序内的数据（插入后）。

Answer 4

 static SqlConnection myConnection; public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { myConnection = new SqlConnection("server=localhost;" + "Trusted_Connection=true;" + "database=zxc; " + "connection timeout=30"); try { myConnection.Open(); label1.Text = "connect successful"; } catch (SqlException ex) { label1.Text = "connect fail"; MessageBox.Show(ex.Message); } } private void Form1_Load(object sender, EventArgs e) { } private void button2_Click(object sender, EventArgs e) { String st = "INSERT INTO supplier(supplier_id, supplier_name)VALUES(" + textBox1.Text + ", " + textBox2.Text + ")"; SqlCommand sqlcom = new SqlCommand(st, myConnection); try { sqlcom.ExecuteNonQuery(); MessageBox.Show("insert successful"); } catch (SqlException ex) { MessageBox.Show(ex.Message); } } 

Answer 5

我刚刚写了一个可重用的方法，这里没有可重复使用的方法，所以为什么不分享…
这是我当前项目的代码：

 public static int ParametersCommand(string query,List parameters) { SqlConnection connection = new SqlConnection(ConnectionString); try { using (SqlCommand cmd = new SqlCommand(query, connection)) { // for cases where no parameters needed if (parameters != null) { cmd.Parameters.AddRange(parameters.ToArray()); } connection.Open(); int result = cmd.ExecuteNonQuery(); return result; } } catch (Exception ex) { AddEventToEventLogTable("ERROR in DAL.DataBase.ParametersCommand() method: " + ex.Message, 1); return 0; throw; } finally { CloseConnection(ref connection); } } private static void CloseConnection(ref SqlConnection conn) { if (conn.State != ConnectionState.Closed) { conn.Close(); conn.Dispose(); } } 

Answer 6

 private void button1_Click(object sender, EventArgs e) { String query = "INSERT INTO product (productid, productname,productdesc,productqty) VALUES (@txtitemid,@txtitemname,@txtitemdesc,@txtitemqty)"; try { using (SqlCommand command = new SqlCommand(query, con)) { command.Parameters.AddWithValue("@txtitemid", txtitemid.Text); command.Parameters.AddWithValue("@txtitemname", txtitemname.Text); command.Parameters.AddWithValue("@txtitemdesc", txtitemdesc.Text); command.Parameters.AddWithValue("@txtitemqty", txtitemqty.Text); con.Open(); int result = command.ExecuteNonQuery(); // Check Error if (result < 0) MessageBox.Show("Error"); MessageBox.Show("Record...!", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information); con.Close(); loader(); } } catch (Exception ex) { MessageBox.Show(ex.Message); con.Close(); } } 

Answer 7

 public static string textDataSource = "Data Source=localhost;Initial Catalog=TEST_C;User ID=sa;Password=P@ssw0rd"; public static bool ExtSql(string sql) { SqlConnection cnn; SqlCommand cmd; cnn = new SqlConnection(textDataSource); cmd = new SqlCommand(sql, cnn); try { cnn.Open(); cmd.ExecuteNonQuery(); cnn.Close(); return true; } catch (Exception) { return false; } finally { cmd.Dispose(); cnn = null; cmd = null; } } 

Answer 8

 class Program { static void Main(string[] args) { string connetionString = null; SqlConnection connection; SqlCommand command; string sql = null; connetionString = "Data Source=Server Name;Initial Catalog=DataBaseName;User ID=UserID;Password=Password"; sql = "INSERT INTO LoanRequest(idLoanRequest,RequestDate,Pickupdate,ReturnDate,EventDescription,LocationOfEvent,ApprovalComments,Quantity,Approved,EquipmentAvailable,ModifyRequest,Equipment,Requester)VALUES('5','2016-1-1','2016-2-2','2016-3-3','DescP','Loca1','Appcoment','2','true','true','true','4','5')"; connection = new SqlConnection(connetionString); try { connection.Open(); Console.WriteLine(" Connection Opened "); command = new SqlCommand(sql, connection); SqlDataReader dr1 = command.ExecuteReader(); connection.Close(); } catch (Exception ex) { Console.WriteLine("Can not open connection ! "); } } }