连接池--在密码修改的影响

群里有朋友问起连接池在密码修改后的变化，特地做了下测试

使用连接池，连接字符串为：

string connString = "Data Source=.;Initial Catalog=DemoDB1;Integrated Security=False;User ID=DBA;Password=XXXXX;Pooling=True;Connect Timeout=60";

测试1

数据库连接打开后不断开(不调用close方法)，连续请求

using (SqlConnection conn = new SqlConnection(connString))
            {
                conn.Open();
                for (int i = 0; i < 100; i++)
                {
                    SqlCommand comm = conn.CreateCommand();
                    comm.CommandText = "SELECT COUNT(1) FROM TB2";
                    comm.CommandType = System.Data.CommandType.Text;
                    Console.WriteLine(comm.ExecuteScalar().ToString());
                    Console.WriteLine(DateTime.Now.ToString());
                    System.Threading.Thread.Sleep(1 * 1000);
                }
            }

测试结果：修改密码后，程序没有任何报错，对已建立的连接没有影响

测试2

循环执行请求，每次请求会关闭链接(using会调用close方法)

for (int i = 0; i < 100; i++)
            {
                using (SqlConnection conn = new SqlConnection(connString))
                {
                    conn.Open();

                    SqlCommand comm = conn.CreateCommand();
                    comm.CommandText = "SELECT COUNT(1) FROM TB2";
                    comm.CommandType = System.Data.CommandType.Text;
                    Console.WriteLine(comm.ExecuteScalar().ToString());
                    Console.WriteLine(DateTime.Now.ToString());
                    System.Threading.Thread.Sleep(1 * 1000);
                }
            }

测试结果：程序运行后，可以使用SQL Profiler捕获到exec sp_reset_connection,当密码修改后，程序立即报错(在命令执行时报错)。

测试3

注释掉执行命令语句，查看conn.Open()是否执行sp_reset_connection

for (int i = 0; i < 100; i++)
            {
                using (SqlConnection conn = new SqlConnection(connString))
                {
                    conn.Open();
                    SqlCommand comm = conn.CreateCommand();
                    comm.CommandText = "SELECT COUNT(1) FROM TB2";
                    comm.CommandType = System.Data.CommandType.Text;
                    //Console.WriteLine(comm.ExecuteScalar().ToString());
                    Console.WriteLine(DateTime.Now.ToString());
                    System.Threading.Thread.Sleep(1 * 1000);
                }
            }

测试结果：无法使用SQL Profiler 捕获到sp_reset_connection

测试4

在重用的连接中执行两次命令，查看是否调用两次sp_reset_connection

for (int i = 0; i < 100; i++)
            {
                using (SqlConnection conn = new SqlConnection(connString))
                {
                    conn.Open();
                    SqlCommand comm = conn.CreateCommand();
                    comm.CommandText = "SELECT COUNT(1) AS COUNT1 FROM TB2";
                    comm.CommandType = System.Data.CommandType.Text;
                    Console.WriteLine(comm.ExecuteScalar().ToString());
                    Console.WriteLine(DateTime.Now.ToString());
                    System.Threading.Thread.Sleep(10 * 1000);
                    comm.CommandText = "SELECT COUNT(1) AS COUNT2 FROM TB2";
                    Console.WriteLine(comm.ExecuteScalar().ToString());
                    System.Threading.Thread.Sleep(10 * 1000);
                }
            }