c# vs2017 Code First与Mysql联系时报错 5C

我在练习写一个code first的demo,连接Mysql数据库。我用migration,在数据库中已经看到了




梅长苏880112 查询过多个帖子。基本确认配置没问题。而且Migration已经通过那个配置,反向生成数据库表了,有问题是不会生成的
大约 2 年之前 回复
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C#中 使用CodeFirst开发模式有什么好处,和先建数据库有什么区别

**C#**中 使用**CodeFirst**开发模式有什么好处,和先建数据库有什么区别


将已经创建好的数据库删除之后,重新创建就会报错表xxx找不到,必须重新启动应用程序才可以创建成功,详细的删除库方法如下: ![图片说明](https://img-ask.csdn.net/upload/201608/30/1472520442_752341.png) 创建库: ![图片说明](https://img-ask.csdn.net/upload/201608/30/1472520754_257715.png)


<div class="post-text" itemprop="text"> <p>I'm writing my first script that will connect via SSL to a MySQL database. I have been doing a lot of reading on the subject and have come across many options on how to set it up; some that apply to my situation and some that don't. Here is my situation:</p> <p>The MySQL server is on the same machine as the script. My SSL Certificate is installed. Is it secure to simply connect to the database via a page that is using SSL with the following code?</p> <pre><code>Connecting via https://www.mysitehere.com/myscript.php $con = mysql_connect("localhost", "username", "password", MYSQL_CLIENT_SSL); if (!$con) {die('Could not connect: ' . mysql_error());} mysql_select_db("my_database", $con); </code></pre> </div>

从C#Windows窗体调用PHP Web服务

<div class="post-text" itemprop="text"> <p>I am trying to verify username, password, and software token number of a C# Windows Form to values in MySQL database. </p> <p>My C# Code:</p> <pre><code> private void btnlogin_Click(object sender, EventArgs e) { if (String.IsNullOrEmpty(txtusername.Text)) { MessageBox.Show("Please insert username"); } if (String.IsNullOrEmpty(txtpassword.Text)) { MessageBox.Show("Please insert password"); } var username = txtusername.Text; var password = txtpassword.Text; string Token = "28956"; var SoftwareToken = token; WebRequest request = WebRequest.Create("https://mydomain.com.au/Verification.php?username=username&amp;password=password&amp;Token=SoftwareToken"); request.Method = "GET"; WebResponse response = request.GetResponse(); Console.WriteLine(((HttpWebResponse)response).StatusDescription); Stream dataStream = response.GetResponseStream(); // Open the stream using a StreamReader for easy access. StreamReader reader = new StreamReader(dataStream); // Read the content. var responseFromServer = reader.ReadToEnd(); responseFromServer.ToArray(); /*I have tried: responseFromServer.ToArray();(because result on php page is an array. I have tried responseFromServer.ToString();*/ MessageBox.Show(responseFromServer); } </code></pre> <p>My PHP code (Web service):</p> <pre><code>&lt;?php // Database Structure require_once('connect.php'); //Get password from the database for the user $stmtus = $conn-&gt;prepare("SELECT password from `Users` where `email` = :Username"); $stmtus-&gt;bindParam(':Username', $username); $username= $_GET['username'];; $stmtus -&gt; execute(); $password = $stmtus-&gt;fetch(); $un = $_GET['username']; $pw = $_GET['password']; $ust = $_GET['Token']; if(password_verify($pw, $password[0])){ $stmt = $conn-&gt;prepare("SELECT COUNT(Token) AS cnt FROM `SoftwareToken` LEFT JOIN User ON iduser = SoftwareToken.Consultant WHERE Token = '$ust' AND username = '$un'"); $stmt-&gt;bindValue(':Username', $un); $stmt-&gt;bindValue(':Token', $ust); $stmt-&gt;execute(); $result= array(); while($SToken= $stmt-&gt;fetch(PDO::FETCH_OBJ)){ array_push($result, $SToken-&gt;cnt); } echo json_encode($result); } $conn = null; ?&gt; </code></pre> <p>I am battling to understand how I call the web service from the C# application, how do I pass the variables from the C# application to the web service and how do I return the json_encode to the C# application from the web service. </p> <p>I am not a full-time programmer and this is my first encounter with web services. If there are any suggestions on how to improve either of the codes, I would much appreciate. </p> <p><strong>UPDATE</strong></p> <p>I have updated my code as assisted. When I run the php code with variables it runs and gives me a $result (array). A numeral answer 1.</p> <p>When I test my code to display the result in a MessageBox, the MessageBox is empty. Why ?</p> </div>

如何将两个MySQL id传递给c#.exe?

<div class="post-text" itemprop="text"> <p>I am trying to make a PDF form filling program. The program should get 2 id's from the PHP script, search the MySQL database, and fill the forms with info based of those two id's, but i cant make the PHP script pass arguments to the c# executable. Maybe u can help me out :)</p> <p>PHP script :</p> <pre><code>&lt;?php $con = mysql_connect("localhost","root",""); if (!$con) { die('Could not connect: ' . mysql_error()); } mysql_select_db("documente", $con); $idfirma; $idagent; $sql="SELECT * FROM `agenti` WHERE `Nume Agent` = '$_GET[numea]'"; $result = mysql_query($sql); while($row = mysql_fetch_array($result)) { echo "Date agent"."&lt;br&gt;"; echo $row['Nume Agent'];echo " | ";echo $row['Sigiliu'];echo " | ";echo $row['Legitimatie']."&lt;br&gt;"."&lt;br&gt;"."&lt;br&gt;"."&lt;br&gt;"."&lt;br&gt;"; $idagent=$row['ID']; } $sql1="SELECT * FROM `dateclienti` WHERE `Cod Fiscal` = '$_GET[codf]'"; $result = mysql_query($sql1); while($row = mysql_fetch_array($result)) { echo "Date Firma"."&lt;br&gt;"; echo $row['Nume Societate'];echo " | ";echo $row['Adresa Sediu'];echo " | ";echo $row['Cod Fiscal']."&lt;br&gt;"; $idfirma=$row['ID']; } exec("pdfgen\PdfGenerator\bin\Debug\PdfGenerator.exe $idfirma, $idagent 2&gt;&amp;1"); echo $idfirma."&lt;br&gt;"."&lt;br&gt;"; echo $idagent; if (!mysql_query($sql,$con)) { die('Error: ' . mysql_error()); } mysql_close($con) ?&gt; </code></pre> <p>c# scipt :</p> <pre><code>using System; using System.Collections; using System.ComponentModel; using System.Data; using System.Drawing; using System.Text; using System.Windows.Forms; using iTextSharp; using iTextSharp.text; using iTextSharp.text.pdf; using iTextSharp.text.xml; using System.IO; using MySql.Data.MySqlClient; namespace PdfGenerator { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void Form1_Load(object sender, EventArgs e) { FillForm(); ListFieldNames(); } /// &lt;summary&gt; /// List all of the form fields into a textbox. The /// form fields identified can be used to map each of the /// fields in a PDF. /// &lt;/summary&gt; private void ListFieldNames() { string pdfTemplate = @"C:\xampp\htdocs\site\pdfgen\PdfGenerator\form.pdf"; // title the form this.Text += " - " + pdfTemplate; // create a new PDF reader based on the PDF template document PdfReader pdfReader = new PdfReader(pdfTemplate); // create and populate a string builder with each of the // field names available in the subject PDF StringBuilder sb = new StringBuilder(); foreach (DictionaryEntry de in pdfReader.AcroFields.Fields) { sb.Append(de.Key.ToString() + Environment.NewLine); } // Write the string builder's content to the form's textbox textBox1.Text = sb.ToString(); textBox1.SelectionStart = 0; } private void FillForm() { string idagent1 = null; string idfirma1 = null; string[] args = System.Environment.GetCommandLineArgs(); if(args.Length !=0) { idfirma1 = args[1]; idagent1 = args[2]; } using (var connection = new MySqlConnection("server = localhost; User Id = root; password = ; database = documente;")) { connection.Open(); string agenti = "SELECT `Nume Agent` FROM `agenti` WHERE `ID` = @id"; string name1 = null; using (var cmd = new MySqlCommand(agenti, connection)) { cmd.Parameters.AddWithValue("@id", idagent1); MySqlDataReader rdr = cmd.ExecuteReader(); DataTable dt = new DataTable(); dt.Load(rdr); foreach (DataRow row in dt.Rows) { string name = row["Nume Agent"].ToString(); name1 = name; } string pdfTemplate = @"C:\xampp\htdocs\site\pdfgen\PdfGenerator\form.pdf"; string newFile = @"C:\xampp\htdocs\site\pdfgen\PdfGenerator\completed_form.pdf"; PdfReader pdfReader = new PdfReader(pdfTemplate); PdfStamper pdfStamper = new PdfStamper(pdfReader, new FileStream( newFile, FileMode.Create)); AcroFields pdfFormFields = pdfStamper.AcroFields; // set form pdfFormFields // The first worksheet and W-4 form pdfFormFields.SetField("topmostSubform[0].Page1[0].regcomert[0]", name1); // flatten the form to remove editting options, set it to false // to leave the form open to subsequent manual edits pdfStamper.FormFlattening = true; // close the pdf pdfStamper.Close(); } } } } } using System; using System.Collections.Generic; using System.Windows.Forms; namespace PdfGenerator { static class Program { /// &lt;summary&gt; /// The main entry point for the application. /// &lt;/summary&gt; [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new Form1()); } } } </code></pre> </div>


<div class="post-text" itemprop="text"> <p>So right now I'm working on a basic session system for my C# Application. I have a table with id,username, password and a session table with id, code, start.</p> <p>the id columns of both tables are relative to the user logged in (id of user table is the same as session table). What I want to do is that when it sets the session it first checks to see if a session is already active, if it is then it will just update the current one, if there isn't one it will insert a new one. This works fine. My problem is that no matter what user I log in as the id is always set to 0 so I can have a max of one session active at a time.</p> <p>Here is what I am currently doing:</p> <pre><code>//get id of inputted user. $id = getUserId($username); //first check if a session already exists that is connected to this username $query = mysql_query("SELECT * FROM sessions WHERE(`id`='$id')") or die("Couldn't query database: &lt;br&gt; &lt;br&gt; " . mysql_error());; if(mysql_num_rows($query) &gt; 0) { //session already exists, update it. mysql_query("UPDATE sessions SET `code`='$code', `start`='$date' WHERE(`id`='$id')") or die("Failed to update session: &lt;br&gt; &lt;br&gt; " . mysql_error()); } else { //session doesn't exist so lets create one mysql_query("INSERT INTO sessions (`id`,`code`,`start`) VALUES('$id','$code', '$date')") or die("Failed to create session: &lt;br&gt; &lt;br&gt; " . mysql_error()); } </code></pre> <p>Also my getUserId function:</p> <pre><code>function getUserId($username) { $query = mysql_query("SELECT * FROM users WHERE(`username`='$username')"); $row = mysql_fetch_row($query); return $row[0]; } </code></pre> <p>My question, if you didn't get it already. Is why is it that the 'id' is always being set to 0 even though the getUserId() function is returning the proper id of the user?</p> <p>Any suggestions?</p> </div>


<div class="post-text" itemprop="text"> <p>I have a c# application that needs to send and retrieve using a PHP file. This PHP file then communicates with the database that the application uses for its data. My problem is, I don't know how to send and get array data between PHP and C#. Below is my code which only process one data, the <strong>student_id</strong>.</p> <p>I tried finding tutorials and solution, and even API's but none could give the exact help I need.</p> <p>Here is my PHP code:</p> <pre><code>class CaptureForm{ ////LOCAL FUNCTION [-&gt;] private function query($sql, $arg, $fetch = false){ require "config.php"; $q = $db-&gt;prepare($sql); $q-&gt;execute($arg); return $fetch ? $q-&gt;fetch(2) : $q; } private function getStud($stud_no){ return $this-&gt;query("SELECT stud_id FROM tbl_students WHERE stud_id COLLATE latin1_bin LIKE ?", array($stud_no), true)["stud_id"]; } ////LOCAL FUNCTION [&lt;-] public function ShowStud($stud_no){ if(empty($stud_no)) return "ERROR:MISSING_PARAMETERS"; return $this-&gt;query("SELECT first_name FROM tbl_students WHERE stud_id = ?", array($this-&gt;getStud($stud_no)), true)["first_name"]; } ////USER FUNCTION [-&gt;] public function CheckWork($stud_no){ //=login if(empty($stud_no)) return "ERROR:MISSING_PARAMETERS"; return "OK:LOGGED_IN"; } </code></pre> <p>and this is my C# code:</p> <pre><code>private void btn_in_Click(object sender, EventArgs e) { if (Execute("CheckWork", "stud_no=" + stud_num.Text) == 1) { stud_no = stud_num.Text; //To pass it to any other froms (=global) //same for pass WebClient fetchInfo = new WebClient(); string studno = fetchInfo.DownloadString("http://localhost/server_api/clog.php?action=showStud&amp;stud_no=" + stud_no); if (studno == "Michelle") { MessageBox.Show("You are logged in! Yay!", "Logged in", MessageBoxButtons.OK, MessageBoxIcon.Information); } else { MessageBox.Show("You are logged in!", "Logged in", MessageBoxButtons.OK, MessageBoxIcon.Information); } } } </code></pre> <p>Both codes are working very well but as I said, can only process one data. I expect to have an array of data to be sent to PHP then to the database and back from PHP to C# then output it as broken down strings. You can send the answer if you know or any other solution/tutorial that you can give. Thank you very much!!</p> </div>

winform开发VS2012使用ADO添加实体模型 相关

连接MySql数据库,选择相应的数据库表。生成的edmx文件下多了两个tt文件,Designer中无数据,翻阅网页:删除两个tt文件,设置edmx的属性——代码生成策略改为默认值; 然后实例化生成的entities: 例如: using (Entities en = new Entities()) { var lst = en.party_businesspartners.First(s => s.id == Guid.Parse("0813ccc3-903a-11e1-89c8-5cf3fc4a687c")); } 抛出异常未将应用对象设置到对象实例…… 请大家多多发言,多多指点……


在程序包管理控制台运行: Add Migration InitialCreate ,生成的文件删除后如何重新添加 注:删除部分文件后:重新 Add Migration InitialCreate后, pm>update-database 数据库,因为找不到部分已经删除的部分文件内容报错

too long

<div class="post-text" itemprop="text"> <p>I'm building a simple application that requires login. At the moment I'm connecting to my database directly from my C# application however, the college network on which this will be used doesn't allow direct connections to MySQL for some reason. I decided to take a look at how I would do this from PHP instead. I've build a simple login form and tested it and it seems to work. However I have some questions and issues that need sorting out.</p> <p>How would I first of all stop just anyone typing in the address of the PHP file and getting the data back?</p> <p>Second, how will I be able to get multiple results back? Let's say I make a PHP file that gets all of the user's files and stores them in the C# application, how do I actually parse this from the PHP file?</p> <p>Here is an example of a login.php file I would have on the server:</p> <pre><code> &lt;?php include("connect.php"); $username = mysql_escape_string($_GET['username']); $password = mysql_escape_string($_GET['password']); $squery = mysql_query("SELECT * FROM users WHERE username='$username'"); $query = mysql_fetch_array($squery); $rowcount = mysql_num_rows($squery); if($rowcount == 1) { if($password != $query['password']) echo'Password errata'; else echo 'Login avvenuto'; } else echo 'Account non registrato'; ?&gt; </code></pre> <p>And here is the code I'd use on C# to access the PHP file:</p> <pre><code>string Reply = new WebClient().DownloadString("" + textBox1.Text + "&amp;password=" + textBox2.Text); switch (Reply.ToLower()) { case "account non registrato": { MessageBox.Show("Account not registered!"); break; } case "password errata": { MessageBox.Show("Password error!"); break; } case "login avvenuto": { MessageBox.Show("Login happened!"); break; } default: { MessageBox.Show("Error with the remote server, please let try again later!"); break; } } </code></pre> <p>Sorry if this question is a bit confusing, I basically just need to know how to correctly manipulate a database with PHP using C# with correct security in place.</p> </div>

如果第一行不为空,如何将值插入第二行? 数据库

<div class="post-text" itemprop="text"> <p>I should insert value to <code>parnerCode2</code> if <code>parnerCodeOwner1</code> already taken value;</p> <p>Below code only inserts to <code>parnerCodeOwner1</code> if new values comes it rewrites first one, It shouldn't rewritten, value should inserted to <code>parnerCode2</code></p> <pre><code>&lt;?php if (isset($_POST['partnerCode'])) { // receive all input values from the form $partnerCode= mysqli_real_escape_string($db, $_POST['partnerCode']); if (empty($partnerCode)) { array_push($errors, "CODE required"); } $user_check_query = "SELECT * FROM refer WHERE partnerCode='$partnerCode' LIMIT 1"; $result = mysqli_query($db, $user_check_query); $user = mysqli_fetch_assoc($result); if (count($errors) == 0) { $query = "update refer set partnerCodeOwner1= '" . $_SESSION['username'] . "' where randomfield='$partnerCode' "; mysqli_query($db, $query); } } ?&gt; </code></pre> <p></p> <pre><code>ID randomfield parnerCode2 parnerCodeOwner1 +-------+-------------+-------------+----------------+ | 1 | uOxerUg4 | | BuBI9vk | +-------+-------------+-------------+----------------+ | 2 | cZzuJlcs | | uOxerUg4 | +-------+-------------+-------------+----------------+ | 3 | BuBI9vke | | cZzuJlcs | +-------+-------------+-------------+----------------+ </code></pre> </div>

其他信息: Keyword not supported: 'port'

![图片说明](https://img-ask.csdn.net/upload/201705/15/1494834202_942974.png) 如图,跪求各位大神帮忙解决


<div class="post-text" itemprop="text"> <p>I'm new to programming and wrote a basic login script <em>(or rather watched a tutorial)</em>, but my output in Unity is at first "User nicht gefunden" and about one second later "User gefunden". </p> <p>My question: Can I somehow wait for a response from the mysql server in a easy way and still recognize a missing connection?</p> <p>Unityscript:</p> <pre><code>public string inputusername; public string inputpassword; public string URL = "http://localhost/login.php"; void Start () { } void Update () { if (Input.GetKeyDown(KeyCode.L)) { StartCoroutine(LoginToDB(inputusername, inputpassword)); } } IEnumerator LoginToDB(string username, string password) { WWWForm form = new WWWForm(); form.AddField("usernamePost", username); form.AddField("passwordPost", password); WWW www = new WWW(URL, form); yield return www; if(www.text == "wrong") { Debug.Log("User nicht gefunden"); } if(www.text == "correct") { Debug.Log("User gefunden"); } } </code></pre> <p>Phpscript:</p> <pre><code>$servername = "localhost"; $username = "root"; $password = "********"; $dbName = "test"; $user_username = $_POST["usernamePost"]; $user_password = $_POST["passwordPost"]; $conn = new mysqli($servername, $username, $password, $dbName); if(!$conn){ die("Verbindung Fehlgeschlagen!". mysqli_connect_error()); } $sql = "SELECT password FROM users WHERE username = '".$user_username."' "; $result = mysqli_query($conn, $sql); if(mysqli_num_rows($result) &gt; 0){ while($row = mysqli_fetch_assoc($result)){ if($row['password'] == $user_password){ echo "correct"; } else{ echo "wrong"; } } }else { echo"not here"; } </code></pre> <p>Sorry in advance for the probably simple question.</p> </div>

从C#访问php soapservice

<div class="post-text" itemprop="text"> <p>well i wanted to make a simple webservice that searches the db and return the data i know i can do it with mysql connector but this is just to learn how to use soaps here is the code for php soap server </p><pre><code>require_once ('lib/nusoap.php'); $namespace = "http://localhost/webservice/index.php?wsdl"; $server = new soap_server(); $server-&gt;configureWSDL("DBQuery"); $server-&gt;wsdl-&gt;schemaTargetNamespace = $namespace; $server-&gt;register( 'QueryMsg', array('name'=&gt;'xsd:string'), array('return'=&gt;'xsd:string'), $namespace, false, 'rpc', 'encoded', 'returns data from database'); function QueryMsg($query) { $con=mysqli_connect('localhost','root','','webserivce'); if (mysqli_connect_errno()) { return "Failed to connect to MySQL: " . mysqli_connect_error(); } if(!isset($query) or strpos(strtolower($query),'select')&lt;=-1) { return "invalid order"; } else { mysqli_real_escape_string($con,$query); $result = mysqli_query($con,$query); while($row = mysqli_fetch_array($result)) { $data[] = $row;} return json_encode($data); } } // create HTTP listener $HTTP_RAW_POST_DATA = isset($HTTP_RAW_POST_DATA) ? $HTTP_RAW_POST_DATA : ''; $server-&gt;service($HTTP_RAW_POST_DATA); exit(); ?&gt; </code></pre> <p>it works when i try calling it from a php soap client but when i try adding this http:// localhost /webservice/index.php in visual studio as service refernce to consume it from C# application i get an error here it is </p> <pre><code>The HTML document does not contain Web service discovery information. Metadata contains a reference that cannot be resolved: 'http://localhost/webservice/index.php'. The content type text/xml; charset=ISO-8859-1 of the response message does not match the content type of the binding (application/soap+xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly. The first 700 bytes of the response were: '&lt;?xml version="1.0" encoding="ISO-8859-1"?&gt;&lt;SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"&gt; &lt;SOAP-ENV:Body&gt;&lt;SOAP-ENV:Fault&gt;&lt;faultcode xsi:type="xsd:string"&gt;SOAP-ENV:Client&lt;/faultcode&gt;&lt;faultactor xsi:type="xsd:string"&gt;&lt;/faultactor&gt;&lt;faultstring xsi:type="xsd:string"&gt;Operation &amp;apos;&amp;apos; is not defined in the WSDL for this service&lt;/faultstring&gt;&lt;detail xsi:type="xsd:string"&gt;&lt;/detail&gt;&lt;/SOAP-ENV:Fault&gt;&lt;/SOAP-ENV:Body&gt;&lt;/SOAP-ENV:Envelope&gt;'. The remote server returned an error: (500) Internal Server Error. If the service is defined in the current solution, try building the solution and adding the service reference again. </code></pre> <p>solved : well it was easy actually there is two ways either use WCF and change encoding to ISO-8859-1 or change encoding of the web service itself by adding this line <code>$server-&gt;soap_defencoding = 'UTF-8';</code> after creating the soap server</p> </div>

连接到数据库和在Visual Studio Windows窗体中获取数据的问题

<div class="post-text" itemprop="text"> <p>I have a combo box that's supposed to output the main category (has 4 rows) then also output the sub category under it (ex. 3 sub categories under the first main category, 5 sub categories under the second main category and so on). </p> <p>My First Code displays the main category correctly (the combobox has 4 results)</p> <pre><code>private void Form1_Load(object sender, EventArgs e) { sc.Open(); //For Main Category SqlCommand get_maincategory_name = new SqlCommand("SELECT * FROM maincategory", sc); SqlDataReader dr2 = get_maincategory_name.ExecuteReader(); while (dr2.Read()) { comboBox1.Items.Add(dr2["maincategory_name"].ToString()); } sc.Close(); } </code></pre> <p>But I tried inserting another loop for the sub category under the while loop of the main category but all I'm getting on the combo box is the first row of the main category (the combobox only has 1 result which is the first row from the main category table)</p> <p>The code I used was:</p> <pre><code>private void Form1_Load(object sender, EventArgs e) { sc.Open(); //For Main Category SqlCommand get_maincategory_name = new SqlCommand("SELECT * FROM maincategory", sc); SqlDataReader dr2 = get_maincategory_name.ExecuteReader(); while (dr2.Read()) { comboBox1.Items.Add(dr2["maincategory_name"].ToString()); //For Sub Category int got_category_id = Convert.ToInt32(dr2["maincategory_id"]); SqlCommand get_subcategory_name = new SqlCommand("SELECT * FROM subcategory WHERE maincategory_id='got_category_id'", sc); SqlDataReader dr3 = get_subcategory_name.ExecuteReader(); while (dr3.Read()) { comboBox1.Items.Add(dr3["subcategory_name"].ToString()); } } sc.Close(); } </code></pre> <p>The only programming experience I have is on php so I tried creating my intended code on PHP and it worked perfectly but I'm having troubles applying it to C# in Visual Studio, here's my code if you guys are wondering what I'm trying to achieve:</p> <pre><code>echo "&lt;select&gt;"; // FOR MAIN CATEGORY $maincategory_query = mysqli_query($con,"SELECT * FROM maincategory") or mysqli_error(); while($got = mysqli_fetch_assoc($maincategory_query)) { $maincategory_id = $got['maincategory_id']; $maincategory_name = $got['maincategory_name']; echo "&lt;option disabled&gt;$maincategory_name&lt;/option&gt;"; // FOR SUB CATEGORY $subcategory_query = mysqli_query($con,"SELECT * FROM subcategory WHERE maincategory_id='$maincategory_id'") or mysqli_error(); while($got = mysqli_fetch_assoc($subcategory_query)) { $subcategory_id = $got['subcategory_id']; $subcategory_name = $got['subcategory_name']; echo "&lt;option disabled&gt;--$subcategory_name&lt;/option&gt;"; // FOR ITEM $item_query = mysqli_query($con,"SELECT * FROM item WHERE subcategory_id='$subcategory_id'") or mysqli_error(); while($got = mysqli_fetch_assoc($item_query)) { $item_id = $got['item_id']; $item_name = $got['item_name']; echo "&lt;option&gt;----$item_name&lt;/option&gt;"; } } } echo "&lt;/select&gt;"; </code></pre> <p>My Concerns:</p> <ol> <li><p>I don't actually know what's happening on why my second code is only doing the loop once and what's worse is it doesn't even display the sub category (the <code>maincategory_id='got_category_id'</code> beside the WHERE in my sql statement was only a placeholder and I tried replacing it by <code>maincategory_id='1'</code> just to check in hopes of it trying to at least check if it's displaying the sub category to no avail. I actually don't know the proper syntax to insert an integer inside a sql statement in Visual Studio but nevertheless, setting it to a value of '1' still doesn't display anything).</p></li> <li><p>What is the proper syntax on inserting an integer inside a sql statement in Visual Studio? I researched and tried putting the &amp; at the beginning and end of the variable but it isn't working.</p></li> </ol> </div>

结合PHP Webservice和C#Client

<div class="post-text" itemprop="text"> <p>I have a C#/Winforms application using PHP webservices. A first PHP webservice uploadFile.php is used to upload a blob file (by a unix application for example) on a mysql database and another webservice, getFile.php (code below), is used to get the file if a file is available for the client.</p> <p>For the moment the client calls every 5 seconds the webservice. Obviously Apache cannot deal with all the connections and gets slow and is often down or timeout, Today I have counted 2000 connections in 2 minutes, and 100 000 in 25 minutes. 99% of them return no file. </p> <p>So instead of calling every 5 (or 10 or 20 or else) seconds the webservice, I would like the webservice uploadFile to notify the client when a result is available. I'm not familiar with SOAP/REST or any other kind of webservices, and for practical reasons (old versions of the application still running) I could not replace the current webservice with REST. Here is what currently does the webservice getOK.php :</p> <pre><code> if(getJobsForUser($login, $serveur)){ //data is BLOB content $query = "SELECT idjob,fileName,data FROM JobSpool WHERE idcompte=$idcompte LIMIT 1" ; $stmt = $pdo-&gt;query($query); $res = $stmt-&gt;fetch(PDO::FETCH_BOTH); $idjob = $res[0] ; $nomfic = $res[1] ; $data = $res[2] ; //send datas to client echo $nomfic." " ; echo $data ; } function checkJobsforUser($login, $serveur){ global $pdo, $idcompte; $query = "SELECT count(*),c.idcompte FROM Compte as c,Job as j WHERE c.login='$login' AND c.serveur = '$serveur' AND j.idcompte = c.idcompte" ; $stmt = $pdo-&gt;query($query); $results = $stmt-&gt;fetch(PDO::FETCH_BOTH); //print_r($results); $count = $results[0]; $idcompte = $results[1]; //echo "count : $count, idcompte : $idcompte &lt;br/&gt;"; if($count &gt; 0) return true; return false; </code></pre> <p>}</p> <p>C# code :</p> <pre><code>public String getMyFile(){ String nomFicFinal = String.Empty; try { HttpWebRequest hwr; String request = "http://myWebServiceDomain.com/getFile.php?login=myLogin&amp;otherId=myOtherId"; hwr = (HttpWebRequest)HttpWebRequest.Create(request); using (HttpWebResponse hwrep = (HttpWebResponse)hwr.GetResponse()) { //read datas br = new BinaryReader(hwrep.GetResponseStream()); Byte[] tmp = new Byte[256]; int b = br.Read(); while (b != -1) { if (b == 10) break; tmp[indNomFic++] = (Byte)b; b = br.Read(); } //get filename nomFicFinal = System.Text.Encoding.ASCII.GetString(tmp, 0, indNomFic); //if parsed data == "0" nothing returned if (nomFicFinal.Length == 1 &amp;&amp; (nomFicFinal.CompareTo("0") == 0 || nomFicFinal.CompareTo("1") == 0)) { br.Close(); nomFicFinal = ""; } else //we parse the content of the request and we create the file with the name nomFicFinal in ApplicationData { nomFicFinal = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData) + @"\MyApp\" + nomFicFinal; bw = new BinaryWriter(File.Open(nomFicFinal, FileMode.Create)); tmp = new Byte[1024]; while ((tmp = br.ReadBytes(1024)) != null) { if (tmp.Length == 0) break; bw.Write(tmp); bw.Flush(); } br.Close(); bw.Close(); } } }catch(Exception ex){ //do something } return nomFicFinal; } </code></pre> <p>I have been searching with "callback PHP C#", etc, but I still do not have a clear idea of what to do for the moment.</p> </div>

sql server 数据库排序规则为: Chinese_PRC_CI_AS 但是中文条件查询不加N查不出来的原因?

sql server 数据库排序规则为: Chinese_PRC_CI_AS 但是中文查询必须加N 不加N查不出来 服务器:腾讯虚拟机 windows server 2008 R2 数据库:2008R2 字段数型 nvarchar(100) ![图片说明](https://img-ask.csdn.net/upload/201907/15/1563184220_116753.jpg) ![图片说明](https://img-ask.csdn.net/upload/201907/15/1563184338_738065.jpg) ![图片说明](https://img-ask.csdn.net/upload/201907/15/1563184463_340532.jpg) ![图片说明](https://img-ask.csdn.net/upload/201907/15/1563202015_451248.png)


<div class="post-text" itemprop="text"> <div class="question-status question-originals-of-duplicate"> <p>This question already has an answer here:</p> <ul> <li> <a href="/questions/2973202/mysql-fetch-array-mysql-fetch-assoc-mysql-fetch-row-mysql-num-rows-etc" dir="ltr">mysql_fetch_array()/mysql_fetch_assoc()/mysql_fetch_row()/mysql_num_rows etc… expects parameter 1 to be resource or result</a> <span class="question-originals-answer-count"> 32 answers </span> </li> </ul> </div> <p>I am trying to select data from a MySQL table to show data's in my c# datagridview, but I get one of the following error messages:</p> <blockquote> <p>Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, boolean given in /var/www/html/data.php on line 15</p> </blockquote> <p>This is my PHP code:</p> <pre><code>&lt;?php $servername = "********"; $username = "root"; $password = "pws"; $dbname = "dbs"; $conn = new mysqli($servername, $username, $password, $dbname); if ($conn-&gt;connect_error) { die("Connection failed: " . $conn-&gt;connect_error); } $sql = "SELECT userid,password,first_name,last_name,role,active FROM aster_users"; $result = mysql_query($sql); while($row = mysqli_fetch_array($result)) { $userid=$row['userid']; $password=$row['password']; $first_name=$row['first_name']; $last_name=$row['last_name']; $role=$row['role']; $active=$row['active']; } $conn-&gt;close(); ?&gt; </code></pre> <p>Help me,</p> </div>


<div class="post-text" itemprop="text"> <p>I am experiencing some really weird inconsistencies when executing queries, and was wondering if anyone knew why.</p> <p>Imagine I have a struct defined as follows:</p> <pre><code>type Result struct { Afield string `db:"A"` Bfield interface{} `db:"B"` Cfield string `db:"C"` Dfield string `db:"D"` } </code></pre> <p>And a MySQL Table with the following cols:</p> <pre><code>A : VARCHAR(50) B : INT C : VARCHAR(50) D : VARCHAR(50) </code></pre> <p>The query I would like to execute:</p> <blockquote> <p>SELECT A, B, C, D FROM table WHERE A="a"</p> </blockquote> <p>first way it can be executed: </p> <pre><code>db.Get(&amp;result, `SELECT A, B, C, D FROM table WHERE A="a"`) </code></pre> <p>second way it can be executed:</p> <pre><code>db.Get(&amp;result, `SELECT A, B, C, D FROM table WHERE A=?`, "a") </code></pre> <p>The inconsistencies I am experiencing are as follows: When executing the query the first way, the type of Bfield is <code>int</code>. However, when executing the query the second time, it is <code>[]uint8</code>.</p> <p>This outcome is occurring for example when B is 1.</p> <p><strong>Why is the type of Bfield different depending on how the query is executed?</strong></p> <p>connection declaration:</p> <pre><code>// Connection is an interface for making queries. type Connection interface { Exec(query string, args ...interface{}) (sql.Result, error) Get(dest interface{}, query string, args ...interface{}) error Select(dest interface{}, query string, args ...interface{}) error } </code></pre> <p><strong>EDIT</strong></p> <p>This is also happening using the Go database/sql package + driver. The queries below are assigning <code>Bfield</code> to <code>[]uint8</code> and <code>int64</code> respectively.</p> <blockquote> <p>db is of type *sql.DB</p> </blockquote> <p>query 1: </p> <p><code>db.QueryRow(SELECT A, B, C, D FROM table WHERE A="a").Scan(&amp;result.Afield, &amp;result.Bfield, &amp;result.Cfield, &amp;result.Dfield)</code></p> <p>-- &gt; type of <code>Bfield</code> is <code>[]uint8</code></p> <p>query 2:</p> <p><code>db.QueryRow(SELECT A, B, C, D FROM table WHERE A=?, "a").Scan(&amp;result.Afield, &amp;result.Bfield, &amp;result.Cfield, &amp;result.Dfield)</code></p> <p>--&gt; type of <code>Bfield</code> is <code>int64</code></p> <p><strong>EDIT</strong></p> <p>Something else to note, when chaining multiple WHERE clauses, as long as <em>at least</em> 1 is populated using <code>?</code>, the query will return <code>int</code>. Otherwise if they are all populated in the string, it will return <code>[]uint8</code></p> </div>


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