ADO.NET中的公共函数

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace MyPsbc
{
    class PublicFuntion
    {
        public SqlConnection GetConnection()
        {
            string connstr = "server=cf;database=PSBC,integrated security=yes";
            SqlConnection connection = new SqlConnection(connstr);
            return connection;
        }
        public SqlCommand GetCommand(string sqltext)
        {
            SqlConnection connection = this.GetConnection();
            connection.Open();
            SqlCommand cmd = new SqlCommand(sqltext, connection);
            cmd.ExecuteNonQuery();
            return cmd;
            cmd.Dispose();
        }
        public SqlDataAdapter GetAdapter(string sqltext)
        {
            SqlConnection connection = this.GetConnection();
            SqlDataAdapter da = new SqlDataAdapter(sqltext, connection);
            connection.Open();
            return da;
        }
        public DataSet GetDataSet(string sqltext, string str_tablename)
        {
            SqlConnection connection = this.GetConnection();
            SqlDataAdapter da = new SqlDataAdapter(sqltext, connection);
            connection.Open();
            DataSet ds = new DataSet();
            da.Fill(ds, str_tablename);
            return ds;
        }
        public SqlDataReader GetReader(string sqltext)
        {
            SqlConnection connection = this.GetConnection();
            SqlCommand cmd = new SqlCommand(sqltext, connection);
            connection.Open();
            SqlDataReader reader = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            return reader;
        }

    }
}