只需更改SqlCommand.CommandText，而不是每次都创建一个新的SqlCommand，无需关闭和重新打开连接。

// Create the first command and execute
var command = new SqlCommand("<SQL Command>", myConnection);
var reader = command.ExecuteReader();

// Change the SQL Command and execute
command.CommandText = "<New SQL Command>";
command.ExecuteNonQuery();

下面的方法应该可以起作用。保持一个连接一直打开，只需要创建新的命令并执行它们。

using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();
    using (SqlCommand command1 = new SqlCommand(commandText1, connection))
    {
    }
    using (SqlCommand command2 = new SqlCommand(commandText2, connection))
    {
    }
    // etc
}

只需在连接字符串中启用此属性：
sqb.MultipleActiveResultSets = true;
此属性允许多个数据读取器使用一个打开的连接。

我没有测试过，但主要的想法是什么：请在每个查询中使用分号。

SqlConnection connection = new SqlConnection();
SqlCommand command = new SqlCommand();
connection.ConnectionString = connectionString; // put your connection string
command.CommandText = @"
     update table
     set somecol = somevalue;
     insert into someTable values(1,'test');";
command.CommandType = CommandType.Text;
command.Connection = connection;

try
{
    connection.Open();
}
finally
{
    command.Dispose();
    connection.Dispose();
}

**更新：**您也可以关注Is it possible to have multiple SQL instructions in a ADO.NET Command.CommandText property?

顺便说一句，这很可能是通过SQL注入攻击的，这将是值得阅读的，并相应地调整您的查询。
也许可以考虑为此创建一个存储过程，并使用类似sp_executesql的东西，当需要动态sql时（即未知表名等），它可以提供一些保护。

没有人提到过这一点，但是您也可以使用a分隔您的命令;分号：

using (SqlConnection conn = new SqlConnection(connString))
    {
        using (SqlCommand comm = new SqlCommand())
        {
                comm.Connection = conn;
                comm.CommandText = @"update table ... where myparam=@myparam1 ; " +
                                    "update table ... where myparam=@myparam2 ";
                comm.Parameters.AddWithValue("@myparam1", myparam1);
                comm.Parameters.AddWithValue("@myparam2", myparam2);
                conn.Open();
                comm.ExecuteNonQuery();

        }
    }

多个非查询示例，如果有人感兴趣。

using (OdbcConnection DbConnection = new OdbcConnection("ConnectionString"))
{
  DbConnection.Open();
  using (OdbcCommand DbCommand = DbConnection.CreateCommand())
  {
    DbCommand.CommandText = "INSERT...";
    DbCommand.Parameters.Add("@Name", OdbcType.Text, 20).Value = "name";
    DbCommand.ExecuteNonQuery();

    DbCommand.Parameters.Clear();
    DbCommand.Parameters.Add("@Name", OdbcType.Text, 20).Value = "name2";
    DbCommand.ExecuteNonQuery();
  }
}

在这里你可以找到Postgre的例子，这段代码在一个SQL连接中运行多个SQL命令（更新2列

public static class SQLTest
    {
        public static void NpgsqlCommand()
        {
            using (NpgsqlConnection connection = new NpgsqlConnection("Server = ; Port = ; User Id = ; " + "Password = ; Database = ;"))
            {
                NpgsqlCommand command1 = new NpgsqlCommand("update xy set xw = 'a' WHERE aa='bb'", connection);
                NpgsqlCommand command2 = new NpgsqlCommand("update xy set xw = 'b' where bb = 'cc'", connection);
                command1.Connection.Open();
                command1.ExecuteNonQuery();
                command2.ExecuteNonQuery();
                command2.Connection.Close();
            }
        }
    }

using (var connection = new SqlConnection("Enter Your Connection String"))
    {
        connection.Open();
    
        using (var command = connection.CreateCommand())
        {
            command.CommandText = "Enter the First Command Here";
            command.ExecuteNonQuery();
    
            command.CommandText = "Enter Second Comand Here";
            command.ExecuteNonQuery();

    //Similarly You can Add Multiple
        }
    }

对我很有效。