class SQLHelper

     {

         public SqlConnection conn;

         //<summary>

         //链接、打开数据库

         //</summary>

         public void open()

         {

             string connectionStr = "server = ;database = ;uid = sa;pwd = ";

             conn = new SqlConnection(connectionStr);

             conn.Open();

         }

         //<summary>

         //关闭数据库

         //</summary>

         public void close()

         {

             conn.Dispose();

             conn.Close();

             conn = null;

         }

         //<summary>

         //得到Command对象

         //</summary>

         public SqlCommand GetCommand(string sqlstring)

         {

             SqlCommand cmd = new SqlCommand(sqlstring,conn);

             return cmd;

         }

         //<summary>

         //输入SQL语句，得到DataReader对象

         //</summary>

         public SqlDataReader GetDataReader(string sqlstring)

         {

             open();

             SqlCommand cmd = new SqlCommand(sqlstring,conn);

             SqlDataReader dr = cmd.ExecuteReader();

             return dr;

         }

         //<summary>

         //输入SQL语句，得到DataSet对象

         //</summary>

         public DataSet GetDataSet(string sqlstring)

         {

             open();

             SqlCommand cmd = new SqlCommand(sqlstring,conn);

             SqlDataAdapter sda = new SqlDataAdapter();

             sda.SelectCommand = cmd;

             DataSet ds = new DataSet();

             //string tmpName = tableName.ToString();

             sda.Fill(ds);

             close();

             return ds;

         }

         //<summary>

         //输入SQL语句，得到DataTable对象

         //</summary>

         public DataTable GetDataTable(string sqlstring)

         {

             DataSet ds = GetDataSet(sqlstring);

             DataTable dt = new DataTable();

             dt = ds.Tables[];

             return dt;

         }

         //<summary>

         //执行非查询命令SQl命令

         //</summary>

         public int ExecuteSQL(string sqlstring)

         {

             int count = -;

             open();

             try

             {

                 SqlCommand cmd = new SqlCommand(sqlstring,conn);

                 count = cmd.ExecuteNonQuery();

             }

             catch

             {

                 count = -;

             }

             finally

             {

                 close();

             }

             return count;

         }

         //<summary>

         //输入SQL语句，检查数据表中是否有该数据信息

         //</summary>

         public int GetDataRow(string sqlstring)

         {

             int CountRow = ;

             open();

             SqlCommand cmd = new SqlCommand(sqlstring,conn);

             SqlDataAdapter sda = new SqlDataAdapter();

             sda.SelectCommand = cmd;

             DataSet ds = new DataSet();

             sda.Fill(ds);

             ds.CaseSensitive = false;

             CountRow = ds.Tables[].Rows.Count;

             close();

             return CountRow;

         }

         //<summary>

         //获取单个值

         //</summary>

         public object GetScalar(string sqlstring)

         {

             open();

             SqlCommand cmd = new SqlCommand(sqlstring,conn);

             object result = cmd.ExecuteScalar();

             close();

             return result;

         }

         //<summary>

         //查询某个表的某列的属性数据，并形成列表

         //</summary>

         //<param name="sqlstring">查询SQL语句</param>

         //<param name="m">第m列的属性，整数类型</param>

         //<return>ArrayList类型数据，存储在ArrayList中的一组数据</return>

         public ArrayList GetArrayList(string sqlstring,int m)

         {

             //创建Arraylist对象

             ArrayList array = new ArrayList();

             SqlDataReader dr = GetDataReader(sqlstring);

             while (dr.Read())   //遍历所有结果集

             {

                 //取结果集索引的第m列的值并添加到ArrayList对象中

                 array.Add(dr.GetValue(m));

             }

             return array;   //返回ArrayList对象

         }

         //<summary>

         //对整体数据集实时批量更新

         //<summary>

         //<param name="ds">DataSet</param>

         //<param name="sqlstring">SQL语句</param>

         //<param name="tableName">表名</param>

         //<return>bool变量，表示是否修改成功</return>

         public bool doupdate(DataSet ds, string sqlstring, string tableName)

         {

             bool isUpdateOk = false;

             open();

             //强制资源清理；Using结束后隐式调用

             //Disposable

             using (SqlDataAdapter da = new SqlDataAdapter(sqlstring, conn))

             {

                 //数据库表一定要有主键列，否则此处无法通过

                 SqlCommandBuilder builder = new SqlCommandBuilder(da);

                 try

                 {

                     lock (this)

                     {

                         da.Update(ds,tableName);

                         isUpdateOk = true;

                     }

                 }

                 catch(SqlException ex)

                 {

                     MessageBox.Show(ex.ToString(),"错误提示");

                 }

             }

             close();

             return isUpdateOk;

         }

     }