怎么提取查询出来的值

如何提取查询出来的值
sql = "select ParentId from Tab_System_Area where AreaId=" + Aid +"";

各位大侠 如果 我要用到 ParentId 应该怎样提取出来 .. 麻烦给出详细的代码!
谢谢!

[解决办法]
你返回的是啥啊？
如果是一个DataTable

dt.Rows[0]["ParentId"].ToString()
[解决办法]

C# code

public string connectionString = "server=10.66.66.16;database=db;uid=sa;pwd=aa";public static DataSet Query(string SQLString)        {            using (SqlConnection connection = new SqlConnection(connectionString))            {                DataSet ds = new DataSet();                try                {                    connection.Open();                    SqlDataAdapter command = new SqlDataAdapter(SQLString, connection);                    command.Fill(ds, "ds");                }                catch (System.Data.SqlClient.SqlException ex)                {                    throw new Exception(ex.Message);                }                return ds;            }        }string sql = "select ParentId from Tab_System_Area where AreaId=" + Aid +""; dataset ds=Query(sql);string id= ds.datatables[0].rows[0]["ParentId"].tostring();
[解决办法]
这不查出来了吗~
SqlConnection con = new Sqlconnection(connectionstring);
SqlCommand com = new SqlCommand(con,sql);
SqlReader reader = com.ExecuteReader();
reader里面就读出来了

[解决办法]
try
               {
                   sql = "select ParentId from Tab_System_Area where AreaId=" + Aid +"";  

                   SqlCommand cmd=new SqlCommand(sql,conn);
                   cmd.Connecction.Open();
                   SqlDataReader reader = cmd.ExecuteReader();
                   
                   if (reader.Read())
                   {
                    int id = (int)reader["ParentId "];
                    
                   }
                   reader.Close();

               }
               catch (Exception ex)
               {
                   Logger.LogException(LogComponentConstants.SQLServer, ex.Message);
               }
               finally
               {
                   try
                   {
                       conn.Close();
                   }
                   catch { }
               }