C#操作MYSQL數據庫

1、下載mysql.Data.dll，在解決方案->引用中引入，並在文件頭部引入

using MySql.Data.MySqlClient;

2、創建MySqlConnection對象(鏈接庫)

string connstr = "data source=localhost;database=cs_test;user id=root;password=123456;pooling=false;charset=utf8";//pooling代表是否使用連接池
MySqlConnection conn = new MySqlConnection(connstr);

 3、創建對應操作的MySqlCommand對象（測試數據庫表名characters，屬性列：id，names，passwords）

string sql = "select * from characters";
MySqlCommand cmd = new MySqlCommand(sql,conn);

4、針對不同操作，MySqlCommand對象有三個常用方法

(1)查找多行 : ExecuteReader()方法

返回一個MysqlDataReader對象，包含多個行，可以用其Read方法逐行讀取。

對於每行元素，可以用getXXX()方法讀取屬性值，XXX爲該屬性類型，參數爲屬性名或者該屬性爲這張表的第幾列。

可以用IsDBNull()方法判斷是否爲空，參數只能是該屬性爲這張表的第幾列（即只能是數字）

    conn.Open();
    MySqlDataReader reader = cmd.ExecuteReader();
    Console.WriteLine("id\t姓名\t密碼");
    while (reader.Read())
    {
        Console.Write(reader.GetInt32("id")+"\t");
        if (reader.IsDBNull(1))
        {
            Console.Write("空\t");
        }
        else
        {
            Console.Write(reader.GetString("names")+"\t");
        }
        if (reader.IsDBNull(2))
        {
            Console.Write("空\n");
        }
        else
        {
        Console.Write(reader.GetString("passwords")+"\n");
        }
    }
    conn.Close();

 

(2)查找單個: ExecuteScalar()

返回值爲查找到的元祖第一個屬性，以object類型返回

string sql2 = "select names from characters where id=2";
MySqlCommand cmd2 = new MySqlCommand(sql2,conn);
conn.Open();
string names = cmd2.ExecuteScalar().ToString();
Console.WriteLine(names);
conn.Close();

(3)增、刪、改: ExecuteNonQuery()

返回值爲int，不成功是0，成功是1

 

string sql3 = "insert into characters (names,passwords) values ('XXX','1234456')";
MySqlCommand cmd3 = new MySqlCommand(sql3,conn);
conn.Open();
int s = cmd3.ExecuteNonQuery();
if (s == 0) 
Console.WriteLine("false");
else 
Console.WriteLine("success");
conn.Close();

 

5、完整代碼

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using MySql.Data.MySqlClient;

namespace mysql_test
{
    class mysqlcz{
        public mysqlcz()
        {
            string connstr = "data source=localhost;database=csceshi;user id=root;password=123456;pooling=false;charset=utf8";
            using (MySqlConnection conn = new MySqlConnection(connstr))
            {
                string sql = "select * from characters";
                MySqlCommand cmd = new MySqlCommand(sql,conn);
                conn.Open();
                MySqlDataReader reader = cmd.ExecuteReader();
                Console.WriteLine("id\t姓名\t密碼");
                while (reader.Read())
                {
                    Console.Write(reader.GetInt32("id")+"\t");
                    if (reader.IsDBNull(1))
                    {
                        Console.Write("空\t");
                    }
                    else
                    {
                        Console.Write(reader.GetString("names")+"\t");
                    }

                    if (reader.IsDBNull(2))
                    {
                        Console.Write("空\n");
                    }
                    else
                    {
                        Console.Write(reader.GetString("passwords")+"\n");
                    }
                }
                conn.Close();
                string sql2 = "select names from characters where id=2";
                MySqlCommand cmd2 = new MySqlCommand(sql2,conn);
                conn.Open();
                string names = cmd2.ExecuteScalar().ToString();
                Console.WriteLine(names);
                conn.Close();

                string sql3 = "insert into characters (names,passwords) values ('XXX','1234456')";
                MySqlCommand cmd3 = new MySqlCommand(sql3,conn);
                conn.Open();
                int s = cmd3.ExecuteNonQuery();
                if (s == 0) Console.WriteLine("false");
                else Console.WriteLine("success");
                conn.Close();
            }
            Console.ReadLine();
        }        
        
       
    }
    class Program
    {
        static void Main(string[] args)
        {
            mysqlcz mt = new mysqlcz();
        }
    }
}

 

 6、sql語句參數化

爲防止sql注入，儘量不要使用字符串拼接的方法拼接sql字符串

 

string uname=Console.ReadLine();
string upwd=Console.ReadLine();//獲取用戶輸入
string sql="insert into characters (names,passwords) values (@name,@pwd)";//使用@符構造sql變量
MysqlCommand cmd = new MysqlCommand(sql,conn);
//使用MysqlCommand對象的parameters屬性，該屬性爲像sql語句傳遞的參數集合，使用add方法向其中添加參數，參數以MysqlParameters對象形式傳遞
cmd.parameters.Add(new MysqlParametes("@name",uname));
cmd.parameters.Add(new MysqlParameters("@pwd",upwd));
conn.Open();
cmd.ExecuteNonQuery();
conn.Close();