有時我們在聚合查詢中，經常會有複雜的聚聯查詢。有時表的聚聯查詢SQL 子句比較複雜，DBA 會經常告訴們，能否通過WITH 子句優化。WITH 子句，是對SQL 聚聯查詢的優化。Bitter.Core 支援對MSSQL WITH 子句的支援。示例程式碼如下：

示例DEMO:

public static List<TScoreSearchDto> With_Page_Demo(int type, string studentname)
        {
            #region //聚聯條件分頁查詢  年級的LEFT JOIN 子語句 使用WITH 來替代

            var
 
 withsql = @"WITH grade as(select* from t_Grade where fid=@id)"; //定義WITH 子句
            var sql = @"SELECT   score.FScore,student.FName  as studentName,class.FName as className,grade.FName as  gradeName FROM  dbo.t_StudentScore score
            LEFT JOIN dbo.t_student student  ON score.FStudentId = student.FID
            LEFT JOIN dbo.t_class class ON  student.FClassId=class.FID
            LEFT JOIN grade ON grade.FID=class.FGradeId
 
";

            PageQuery pq = new PageQuery(sql, null);
            pq.AddPreWith(withsql, new { id = 3 });
           


            pq.Where("1=1");

            if (type == 1)
            {
                pq.Where("score.FScore>60 ");
            }
            if (type == 2)
            {
                pq.Where(
 
"score.FScore>60 and score.FScore<80 ");
            }
            if (!string.IsNullOrEmpty(studentname))
            {
                pq.Where(" student.FName like '%' + @FScoreName + '%'", new { FScoreName = studentname });
            }

            //通過ThenAsc 方法指定欄位排序
            pq.ThenASC("score.FScore ");

            //通過ThenDESC 方法指定欄位排序
            pq.ThenDESC("student.FName");

            //自己直接指定排序欄位和排序關鍵詞
            pq.OrderBy("student.FAddTime desc");

            //分頁指定 Skip: 當前頁，Take :每頁數量
            pq.Skip(1).Take(10);

            var dt = pq.ToDataTable(); //獲取資料

            var studentscount = pq.Count(); //獲取當前條件下的數量


            return dt.ToListModel<TScoreSearchDto>(); //ToList<T>() DataTable-->List<T> 的模型轉換


            #endregion

        }

上面的示例程式碼備註圖：