如何使用标准 api 在 nhibernate 中按范围进行分组

Question

我想在 Criteria api 中编写 sql：

SELECT CASE 
WHEN total_pages = 0 THEN '0 pages'
WHEN total_pages BETWEEN 1 AND 3 THEN '1-3 pages'
WHEN total_pages BETWEEN 4 AND 6 THEN '4-6 pages'
WHEN total_pages > 6 THEN '7 + pages'
END AS pagerange, sum(total_pages) AS 'Total'
FROM dbo.connector_log_entry
GROUP BY 
CASE 
WHEN total_pages = 0 THEN '0 pages'
WHEN total_pages BETWEEN 1 AND 3 THEN '1-3 pages'
WHEN total_pages BETWEEN 4 AND 6 THEN '4-6 pages'
WHEN total_pages > 6 THEN '7 + pages'
END
ORDER BY pagerange

Answer 1

var groupBy = @"
    CASE
      WHEN total_pages = 0 THEN '0 pages'
      WHEN total_pages BETWEEN 1 AND 3 THEN '1-3 pages'
      WHEN total_pages BETWEEN 4 AND 6 THEN '4-6 pages'
      WHEN total_pages > 6 THEN '7 + pages'
    END";
var pagerange = Projections.SqlGroupProjection(groupBy + " pagerange",
                                               groupBy,
                                               new[] { "pagerange" },
                                               new[] { NHibernateUtil.String });
var results = session.CreateCriteria<ConnectorLogEntry>()
                     .SetProjection(pagerange,
                                    Projections.Sum("TotalPages"))
                     .List();

假设您的类名为 ConnectorLogEntry，并且映射到total_pages 列的属性名为 TotalPages。

我欠你 ORDER BY 位，但你总是可以在客户端排序。