MySql在Visual Studio 2012中不起作用:找不到类型或名称空间名称'MySql' [英] MySql doesn't work in Visual Studio 2012 : The type or namespace name 'MySql' could not be found

问题描述

给出以下代码:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
//Include mysql client namespace.

using MySql.Data.MySqlClient;   // That one doesn't work !!!
using System.Configuration;

namespace CSharpMySqlSample
{
    public partial class frmMySqlSample : Form
    {
        //Read connection string from application settings file
        string   ConnectionString = ConfigurationSettings.AppSettings["ConnectionString"];
        MySqlConnection connection;
        MySqlDataAdapter adapter;
        DataTable DTItems;
        public frmMySqlSample()
        {
            InitializeComponent();
        }

        private void frmMySqlSample_Load(object sender, EventArgs e)
        {
            //Initialize mysql connection
            connection = new MySqlConnection(ConnectionString);

            //Get all items in datatable
            DTItems = GetAllItems();

            //Fill grid with items
            dataGridView1.DataSource = DTItems;
        }

        //Get all items from database into datatable
        DataTable GetAllItems()
        {
            try
            {
                //prepare query to get all records from items table
                string query = "select * from items";
                //prepare adapter to run query
                adapter = new MySqlDataAdapter(query, connection);
                DataSet DS = new DataSet();
                //get query results in dataset
                adapter.Fill(DS);

                // Set the UPDATE command and parameters.
                adapter.UpdateCommand = new MySqlCommand(
                    "UPDATE items SET ItemName=@ItemName, Price=@Price, AvailableQuantity=@AvailableQuantity, Updated_Dt=NOW() WHERE ItemNumber=@ItemNumber;",
                    connection);
                adapter.UpdateCommand.Parameters.Add("@ItemNumber", MySqlDbType.Int16, 4, "ItemNumber");
                adapter.UpdateCommand.Parameters.Add("@ItemName", MySqlDbType.VarChar, 100, "ItemName");
                adapter.UpdateCommand.Parameters.Add("@Price", MySqlDbType.Decimal, 10, "Price");
                adapter.UpdateCommand.Parameters.Add("@AvailableQuantity", MySqlDbType.Int16, 11, "AvailableQuantity");
                adapter.UpdateCommand.UpdatedRowSource = UpdateRowSource.None;

                // Set the INSERT command and parameter.
                adapter.InsertCommand = new MySqlCommand(
                    "INSERT INTO items VALUES (@ItemNumber,@ItemName,@Price,@AvailableQuantity,NOW());",
                    connection);
                adapter.InsertCommand.Parameters.Add("@ItemNumber", MySqlDbType.Int16, 4, "ItemNumber");
                adapter.InsertCommand.Parameters.Add("@ItemName", MySqlDbType.VarChar, 100, "ItemName");
                adapter.InsertCommand.Parameters.Add("@Price", MySqlDbType.Decimal, 10, "Price");
                adapter.InsertCommand.Parameters.Add("@AvailableQuantity", MySqlDbType.Int16, 11, "AvailableQuantity");
                adapter.InsertCommand.UpdatedRowSource = UpdateRowSource.None;

                // Set the DELETE command and parameter.
                adapter.DeleteCommand = new MySqlCommand(
                    "DELETE FROM items "
                    + "WHERE ItemNumber=@ItemNumber;", connection);
                adapter.DeleteCommand.Parameters.Add("@ItemNumber",
                  MySqlDbType.Int16, 4, "ItemNumber");
                adapter.DeleteCommand.UpdatedRowSource = UpdateRowSource.None;

                //return datatable with all records
                return DS.Tables[0];
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
            return null;
        }

        private void btnSave_Click(object sender, EventArgs e)
        {
            try
            {
                //Save records in database using DTItems which is datasource for Grid
                adapter.Update(DTItems);
                //Refresh grid
                DTItems = GetAllItems();
                dataGridView1.DataSource = DTItems;
                MessageBox.Show("Items saved successfully...");
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }

        private void btnDelete_Click(object sender, EventArgs e)
        {
            if (dataGridView1.SelectedRows.Count > 0)
            {
                //Delete a row from grid first.
                dataGridView1.Rows.Remove(dataGridView1.SelectedRows[0]);

                //Save records again. This will delete record from database.
                adapter.Update(DTItems);

                //Refresh grid. Get items again from database and show it in grid.
                DTItems = GetAllItems();
                dataGridView1.DataSource = DTItems;
                MessageBox.Show("Selected item deleted successfully...");
            }
            else
            {
                MessageBox.Show("You must select entire row in order to delete it.");
            }
        }
    }
}

编译后，我得到:

error CS0246: The type or namespace name 'MySqlConnection' could not be found (are you missing a using directive or an assembly reference?)

但是我检查了连接器:

But I checked the connector :

它已安装..

那怎么了?

谢谢

推荐答案

您需要添加对MySql.Data.dll的引用，但最好使用NuGet

You need to add reference to MySql.Data.dll but it is better you can add this dll as package by using NuGet

下面是程序包管理器控制台"命令

below is the Package Manager Console command

PM> Install-Package MySql.Data

这篇关于MySql在Visual Studio 2012中不起作用:找不到类型或名称空间名称'MySql'的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！