ExecuteScalar 要求已打开且可用的连接。连接的当前状态为已关闭。

Question

我在DBhelper里写的方法以及连接对象：
private static string connectionString = ConfigurationManager.ConnectionStrings["WanDu"].ConnectionString;
        /// <summary>
        /// 连接对象
        /// </summary>
        public static SqlConnection Connection
        {
            get
            {
                return new SqlConnection(connectionString);
            }
        }
方法：public static int GetScalar(string safeSql)
        {
            SqlCommand cmd = new SqlCommand(safeSql, Connection);
            
            try
            {
                Connection.Open();
                int result = Convert.ToInt32(cmd.ExecuteScalar());
                return result;
            }
            finally
            {
                Connection.Close();            }
        }
报错：ExecuteScalar 要求已打开且可用的连接。连接的当前状态为已关闭。
请教各位！！！

Answer 1

 private static SqlConnection cn = null;
private static SqlCommand cmd = null;
        private static SqlConnection GetConn()
        {
            string ConnStr = M_Common.Helper.ConfigHelper.GetconnMsSql.ToString();
            cn = new SqlConnection(ConnStr);
            if (cn.State != ConnectionState.Open)
            {
                cn.Open();
            }
            return cn;
        }
public static int ExecuteScalar(string cmdtext, SqlParameter[] para, CommandType ct)
        {
            int value;
            try
            {
                cmd = new SqlCommand(cmdtext, GetConn());
                cmd.CommandType = ct;
                cmd.Parameters.AddRange(para);
                value = Convert.ToInt32(cmd.ExecuteScalar());
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (cn.State == ConnectionState.Open)
                {
                    cn.Close();
                }
            }
            return value;
        }