connection这么创建的优缺点是什么_ASP.NET

connection这样创建的优缺点是什么
private static SqlConnection con;

/// <summary>
/// 取得连接
/// </summary>
public static SqlConnection Connection
{
get
{
string connectstring = @"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\GameCard_data.mdf;Integrated Security=True;User Instance=True";
if (con == null)
{
con = new SqlConnection(connectstring);
con.Open();
}
else if (con.State == ConnectionState.Broken)
{
con.Close();
con.Open();
}
else if (con.State == ConnectionState.Closed)
{
con.Open();
}
return con;
}
}

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探讨
引用:
最致命的缺点，就是只有一个人能连接数据库。

为什么只有一个人能连接数据库？？

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C# code

using System;using System.Data;using System.Data.SqlClient;using System.Threading;public partial class _Default : System.Web.UI.Page{    protected void Page_Load(object sender, EventArgs e)    {        for (int i = 1; i <= 10; i++)        {            Response.Write("start:" + i.ToString());            new Thread(new ThreadStart(MyThread)).Start();        }        for (int i = 1; i <= 10; i++)        {            Response.Write("start:" + i.ToString());            new Thread(new ThreadStart(TestThread)).Start();        }    }    private static string connectstring = @"Data Source=127.0.0.1;Initial Catalog=XXXXXX;Persist Security Info=True;User ID=sa;Password=sa";    private static SqlConnection con;    /// <summary>    /// 取得连接    /// </summary>    public static SqlConnection Connection    {        get        {            if (con == null)            {                con = new SqlConnection(connectstring);                con.Open();            }            else if (con.State == ConnectionState.Broken)            {                con.Close();                con.Open();            }            else if (con.State == ConnectionState.Closed)            {                con.Open();            }            return con;        }    }    static void MyThread()    {        try        {            var sql = "SELECT * FROM table1";            SqlCommand cmd = new SqlCommand(sql, Connection);            SqlDataReader reader = cmd.ExecuteReader();            while (reader.Read())            {                Console.WriteLine(reader["mc"].ToString());            }            reader.Close();        }        catch (Exception ex)        {                 }    }    static void TestThread()    {        var sql = "SELECT * FROM table1";        using (SqlConnection myconn = new SqlConnection(connectstring))        {            myconn.Open();            SqlCommand cmd =new SqlCommand(sql,myconn);            SqlDataReader reader = cmd.ExecuteReader();            while (reader.Read())            {                Console.WriteLine(reader["mc"].ToString());            }            reader.Close();        }    }}
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缺点：
1.使用static，也就是全局能使用，如果有多线程，那么大家都来争这个资源，建议你可以在控制台中模拟多线程来测试一下，特别是两个线程几乎差不多时间进入此代码获取connection，你可以看看会怎样。
2.把connectstring放在代码里面，任何线程（用户）来调用的时候，都会产生新的字符串。这有点浪费内存