C# Visual Studio 和多个 mySQL 查询答案

【问题标题】：C# visual studio and multiple mySQL query'sC# Visual Studio 和多个 mySQL 查询
【发布时间】：2016-03-05 22:31:42
【问题描述】：

刚开始编写 C# 代码，我绝对是它的初学者。话虽如此，我有一个关于使用 MySqlConnector 和 mysql 查询的问题。

我目前有一个查询，我用它填充了一个列表框的结果。但我喜欢做的是向阅读器添加更多查询，并将其他查询的结果放在组合框中。那么我该怎么做呢？我搜索了谷歌并没有找到答案。

    using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace Badminton_stand
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }


        private void timer1_Tick(object sender, EventArgs e)
        {
            labelCurrentTime.Text = DateTime.Now.ToString();
        }



        private void Form1_Load(object sender, EventArgs e)
        /*  {
              string MyConString = "Server=localhost;Port=3307;Database=database1;UID=root;Password=toor";
              MySqlConnection connection = new MySqlConnection(MyConString);
              MySqlCommand command = connection.CreateCommand();
              MySqlDataReader Reader;
              command.CommandText = @"select Club from teams;
                  select team from teams";
              connection.Open();
              Reader = command.ExecuteReader();
              while (Reader.Read())
              {
                  string thisrow = "";
                  for (int i = 0; i < Reader.FieldCount; i++)
                      thisrow += Reader.GetValue(i).ToString() + " ";
                  clubSelectorBox1.Items.Add(thisrow);
              }
              while (Reader.NextResult()) ;
              {
                  string thisrow = "";
                  for (int i = 0; i < Reader.FieldCount; i++)
                      thisrow += Reader.GetValue(i).ToString() + " ";
                  cbTeam1.Items.Add(thisrow); 
              }
              connection.Close();
          } */
        {
            string cmdText = @"SELECT Club from teams;
                   SELECT team from teams";
            using (MySqlConnection cnn = new MySqlConnection("Server=localhost;Port=3307;Database=badminton;UID=root;Password=usbw"))
            using (MySqlCommand cmd = new MySqlCommand(cmdText, cnn))
            {
                cnn.Open();
                using (MySqlDataReader reader = cmd.ExecuteReader())
                {
                    do
                    {
                        while (reader.Read())
                        {
                            string thisrow = "";
                            for (int i = 0; i < reader.FieldCount; i++)
                                thisrow += reader.GetValue(i).ToString() + " ";
                            clubSelectorBox1.Items.Add(thisrow);
                        }

                    }
                    while (reader.NextResult());
                    {

                    }
                }
            }

        }
    }
}

提前致谢！

【问题讨论】：

标签： c# mysql winforms

【解决方案1】：

您可以在查询文本中放置多个 SELECT 语句，并使用 MySqlDataReader 的 NextResult 方法循环遍历结果。

这是一个如何做的例子，当然你应该适应你的数据和控件

string cmdText = @"SELECT * from TABLE_A;
                   SELECT * from TABLE_B";
using(MySqlConnection cnn = new MySqlConnection(......))
using(MySqlCommand cmd = new MySqlCommand(cmdText, cnn))
{
    int curTable = 0;
    cnn.Open();
    using(MySqlDataReader reader = cmd.ExecuteReader())
    {
        do
        {
            while (reader.Read())
            {
                if(curTable == 0)
                    Console.WriteLine("Update first list based on the first table");
                else if(curTable == 1)
                    Console.WriteLine("Update second list based on second table");
            }
            Console.WriteLine("Go to next result");
            curTable++;
        }
        while(reader.NextResult());
    }
}

【讨论】：

这就是我要找的！谢谢史蒂夫
试图让它与我想要的一起工作，但它不起作用。当我遍历 reader.Read 时，它还会从第二个查询字符串中获取结果并将其放在我的 listBox 中。你能帮帮我吗？有关更新的代码，请参阅我的第一篇文章。
现在有点忙，你应该保留当前循环的计数器并更新正确的列表

【解决方案2】：

使用函数。

 private void Form1_Load(object sender, EventArgs e)
        {
            LoadCombo(clubSelectorbox1, "select club from teams");
            //now just change the control and the query as needed
            LoadCombo(clubSelectorbox2, "select club from teams");
        }

 private function LoadCombo(DropDownControl myCombo, string query){
string MyConString = "Server=localhost;Port=3307;Database=database1;UID=root;Password=toor";
            MySqlConnection connection = new MySqlConnection(MyConString);
            MySqlCommand command = connection.CreateCommand();
            MySqlDataReader Reader;
            command.CommandText = query; // use query here
            connection.Open();
            Reader = command.ExecuteReader();
            while (Reader.Read())
            {
                string thisrow = "";
                for (int i = 0; i < Reader.FieldCount; i++)
                    thisrow += Reader.GetValue(i).ToString() + " ";

                myCombo.Items.Add(thisrow); //use myControl here
            }
            connection.Close();
       }

【讨论】：

【解决方案3】：

为每个附加查询初始化一个新的 MySqlCommand。

MySqlCommand command2 = connection.CreateCommand();
command2.CommandText = ""; // here the new query

【讨论】：