private static Exp Junction(Exp exp1, Exp exp2, bool and)
 {
     if (exp1 == null && exp2 == null) return null;
     if (exp1 == null) return exp2;
     if (exp2 == null) return exp1;
     return new JunctionExp(exp1, exp2, and);
 }

        private List<File> GetFiles(Exp where)
        {
            var q = Query("wiki_files")
                .Select("filename", "uploadfilename", "version", "userid", "date", "filelocation", "filesize")
                .Where(where)
                .OrderBy("filename", true);

            return db
                .ExecuteList(q)
                .ConvertAll(r => ToFile(r))
                .GroupBy(f => f.FileName)
                .Select(g => g.OrderByDescending(f => f.Version).First())
                .ToList();
        }

        private SqlQuery GetAccountQuery(Exp where)
        {
            SqlQuery sqlQuery = Query("sm_facebookaccounts")
                .Select(
                    "access_token",
                    "user_id",
                    "associated_id",
                    "user_name"
                );

            if (where != null)
                sqlQuery.Where(where);

            return sqlQuery;
        }

        private SqlQuery GetSqlQuery(Exp where)
        {
            var sqlQuery = new SqlQuery("crm_currency_info")
                .Select("resource_key",
                        "abbreviation",
                        "symbol",
                        "culture_name",
                        "is_convertable",
                        "is_basic");

            if (where != null)
                sqlQuery.Where(where);

            return sqlQuery;
        }

        private SqlQuery GetAccountQuery(Exp where)
        {
            SqlQuery sqlQuery = Query("sm_twitteraccounts")
                .Select(
                    "access_token",
                    "access_token_secret",
                    "screen_name",
                    "user_id",
                    "associated_id",
                    "user_name"
                );

            if (where != null)
                sqlQuery.Where(where);

            return sqlQuery;
        }

        private IEnumerable<TenantQuota> GetTenantQuotas(Exp where)
        {
            var q = new SqlQuery(tenants_quota)
                .Select("tenant", "name", "description", "max_file_size", "max_total_size", "active_users", "features", "price", "avangate_id")
                .Where(where);

            return ExecList(q)
                .ConvertAll(r => new TenantQuota(Convert.ToInt32(r[0]))
                {
                    Name = (string)r[1],
                    Desc = (string)r[2],
                    MaxFileSize = GetInBytes(Convert.ToInt64(r[3])),
                    MaxTotalSize = GetInBytes(Convert.ToInt64(r[4])),
                    ActiveUsers = Convert.ToInt32(r[5]) != 0 ? Convert.ToInt32(r[5]) : int.MaxValue,
                    Features = (string)r[6],
                    Price = Convert.ToDecimal(r[7]),
                    AvangateId = (string)r[8],
                });
        }

 private List<MailTag> GetMailTags(int id_tenant, string id_user, Exp exp)
 {
     using (var db = GetDb())
     {
         return GetMailTags(db, id_tenant, id_user, exp);
     }
 }

        private SqlQuery GetListItemSqlQuery(Exp where)
        {
            var result = Query("crm_list_item")
               .Select(
                   "id",
                   "title",
                   "description",
                   "color",
                   "sort_order",
                   "additional_params",
                   "list_type"
               );

            if (where != null)
                result.Where(where);

            return result;

        }

        private SqlQuery GetTaskQuery(Exp where)
        {
            return GetTaskQuery(where, String.Empty);

        }

        private SqlQuery GetInvoiceSqlQuery(Exp where,  String alias)
        {
            var sqlQuery = Query("crm_invoice");

            if (!String.IsNullOrEmpty(alias))
            {
                sqlQuery = new SqlQuery(String.Concat("crm_invoice ", alias))
                           .Where(Exp.Eq(alias + ".tenant_id", TenantID));
                sqlQuery.Select(GetInvoiceColumnsTable(alias));

            }
            else
            {
                sqlQuery.Select(GetInvoiceColumnsTable(String.Empty));
            }

            if (where != null)
                sqlQuery.Where(where);

            return sqlQuery;
        }

        private SqlQuery GetRelationshipEventQuery(Exp where)
        {
            SqlQuery sqlQuery = Query("crm_relationship_event")
               .Select("id",
                       "contact_id",
                       "content",
                       "entity_id",
                       "entity_type",
                       "create_on",
                       "create_by",
                       "category_id"
                  );

            if (where != null)
                sqlQuery.Where(where);

            return sqlQuery;
        }

 public static Exp Or(Exp exp1, Exp exp2)
 {
     return Junction(exp1, exp2, false);
 }

 public SqlUpdate Where(Exp where)
 {
     this.where = this.where & where;
     return this;
 }

        private SqlQuery GetContactSqlQuery(Exp where)
        {
            return GetContactSqlQuery(where, String.Empty);

        }

 public SqlDelete Where(Exp where)
 {
     this.where = this.where & where;
     return this;
 }

        private SqlQuery GetFieldDescriptionSqlQuery(Exp where)
        {
            var sqlQuery = Query("crm_field_description")
                .Select("id",
                        "-1",
                        "label",
                        "' '",
                        "type",
                        "sort_order",
                        "mask",
                        "entity_type")
                .OrderBy("sort_order", true);

            if (where != null)
                sqlQuery.Where(where);

            return sqlQuery;
        }

 protected SqlQuery GetFolderQuery(Exp where)
 {
     return Query("files_folder f")
         .Select("f.id")
         .Select("f.parent_id")
         .Select("f.title")
         .Select("f.create_on")
         .Select("f.create_by")
         .Select("f.modified_on")
         .Select("f.modified_by")
         .Select("f.folder_type")
         .Select("f.foldersCount")
         .Select("f.filesCount")
         .Select(GetRootFolderType("parent_id"))
         .Select(Exp.Exists(GetSharedQuery(FileEntryType.Folder)))
         .Where(@where);
 }

        private SqlQuery GetCasesSqlQuery(Exp where)
        {
            var sqlQuery = Query("crm_case")
                .Select("id", "title", "create_by", "create_on", "is_closed");

            if (where != null)
            {
                sqlQuery.Where(where);
            }

            return sqlQuery;
        }

 private SqlQuery GetFeedCommentQuery(Exp where)
 {
     return Query("events_comment").Select("Id", "Feed", "Comment", "Parent", "Date", "Creator", "Inactive").Where(where);
 }

        private SqlQuery GetInvoiceLineSqlQuery(Exp where)
        {
            var sqlQuery = Query("crm_invoice_line")
                .Select(
                    "id",
                    "invoice_id",
                    "invoice_item_id",
                    "invoice_tax1_id",
                    "invoice_tax2_id",
                    "sort_order",
                    "description",
                    "quantity",
                    "price",
                    "discount");

            if (where != null)
            {
                sqlQuery.Where(where);
            }

            return sqlQuery;
        }