Data addition, deletion and modification

namespace DAL
{
    class SqlHelper
    {

        static string conString = "server=.;database=SQLSchool;uid=sa;pwd=sasa";

        ///  <summary> 
        /// Execute the query to return the result set
         ///  </summary> 
        ///  <param name="safeSql"> Store procedure name (SQL statement) </param> 
        ///  <param name= "ps"> SQL parameter object collection </param> 
        ///  <returns> table </returns> 
        public  static DataTable ExecuteTable( string safeSql, SqlParameter[] ps)
        {
            //using 块
            using (SqlConnection con = new SqlConnection(conString))
            {
                SqlCommand cmd = new SqlCommand(safeSql, con);
                 // The type of setting command is: stored procedure. If not set, the default is the executed text, that is, the ordinary SQL statement 
                cmd.CommandType = CommandType.StoredProcedure;
                 // The default is to execute the ordinary SQL text statement such as: select * from student
                 // cmd.CommandType = CommandType.Text;

                if (ps != null && ps.Length > 0)
                {
                    // Add parameters to the collection of command objects 
                    cmd.Parameters.AddRange(ps);
                }
                con.Open();
                SqlDataReader reader = cmd.ExecuteReader();//查询数据：ExecuteReader
                DataTable table = new DataTable();
                table.Load(reader);

                reader.Close();
                con.Close();

                return table;
            }
        }

        public  static  object ExecuteSingle( string safeSql, SqlParameter[] ps) // Single object: ExecuteSingle 
        {
             using (SqlConnection con = new SqlConnection(conString))
            {
                SqlCommand cmd = new SqlCommand(safeSql, con);
                cmd.CommandType = CommandType.StoredProcedure;
                if (ps != null && ps.Length > 0)
                {
                    cmd.Parameters.AddRange(ps);
                }
                con.Open();
                object result = cmd.ExecuteScalar();
                con.Close();
                return result;
            }
        }

        public static int ExecuteInsertUpdateDelete(string safeSql, SqlParameter[] ps)
        {
            using (SqlConnection con = new SqlConnection(conString))
            {
                SqlCommand cmd = new SqlCommand(safeSql, con);
                cmd.CommandType = CommandType.StoredProcedure;
                if (ps != null && ps.Length > 0)
                {
                    cmd.Parameters.AddRange(ps);
                }
                con.Open();
                int effectedRows = cmd.ExecuteNonQuery(); // Add, delete, modify: ExecuteNonQuery 
                con.Close();
                 return effectedRows;
            }
        }
    }
}