自己写的操作sql的公共类

    /*
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                 女神保佑         永无BUG
*/

    public static class SQLHelper
    {
        private static SqlConnection Con;
        private static SqlCommand cmd;
        private static DataTable dt;
        private static DataSet ds;
        private static SqlDataAdapter da;
        private static string sqlstr;
        private static void SQLHelper()
        {
            sqlstr = "";
        }
        /// <summary>
        /// 执行一个sql语句，返回第一行第一个值
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static object GetFirstValue(string sql)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                Con.Open();
                cmd = new SqlCommand(sql, Con);
                return cmd.ExecuteScalar();
            }
        }
        /// <summary>
        /// 执行一个sql语句，返回受影响行数
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static int GetNonQuery(string sql)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                Con.Open();
                cmd = new SqlCommand(sql, Con);
                return cmd.ExecuteNonQuery();
            }
        }
        /// <summary>
        /// 离线模式填充datatable并返回，数据少可以用此方法
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable GetDataTableA(string sql)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                da = new SqlDataAdapter(sql, Con);
                dt = new DataTable();
                da.Fill(dt);
                return dt;
            }
        }

        /// <summary>
        /// 根据sql,填充datatable并返回。数据多的时候可以用此方法
        /// </summary>
        /// <param name="sql"></param>
        /// <returns></returns>
        public static DataTable GetDataTableB(string sql)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                Con.Open();
                cmd = new SqlCommand(sql, Con);
                dt = new DataTable();
                SqlDataReader reader = cmd.ExecuteReader();
                dt.Load(reader);
                Con.Close();
                return dt;
            }
        }
        /// <summary>
        /// 传入sql语句集，返回一个dataset
        /// </summary>
        /// <param name="sqllist"></param>
        /// <returns></returns>
        public static DataSet GetDataSet(List<string> sqllist)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                Con.Open();
                ds = new DataSet();
                foreach (string  c in sqllist)
                {
                    cmd = new SqlCommand(c, Con);
                    dt = new DataTable();
                    SqlDataReader reader = cmd.ExecuteReader();
                    dt.Load(reader);
                    ds.Tables.Add(dt);
                }
                Con.Close();
                return ds;
            }
        }
        /// <summary>
        /// 在事务中执行多条sql语句
        /// </summary>
        /// <param name="list"></param>
        /// <returns></returns>
        public static bool ExecSQLSList(List<string> list)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                Con.Open();
                SqlTransaction tran = Con.BeginTransaction();
                try
                {
                    foreach (string sql in list)
                    {
                        cmd = new SqlCommand(sql, Con);
                        cmd.ExecuteNonQuery();
                    }
                    tran.Commit();
                    Con.Close();
                    return true;

                }
                catch
                {
                    tran.Rollback();
                    return false;
                }
                finally
                {
                    Con.Close();
                    Con.Dispose();               
                }            
            }
          
        }


        /// <summary>
        /// 执行一个不带参数的存储过程，返回datable
        /// </summary>
        /// <param name="StoredProcedureName"></param>
        /// <returns></returns>
        public static DataTable GetDataTableByStoredProcedure(string StoredProcedureName)
        {
            using (Con = new SqlConnection(sqlstr))
            {
                Con.Open();
                cmd = new SqlCommand();
                cmd.CommandText = StoredProcedureName;
                cmd.CommandType = CommandType.StoredProcedure;
                dt = new DataTable();
                dt.Load(cmd.ExecuteReader());
                return dt;
            }
        }




    }