[英]Hibernate Criteria: Projecting Count with group by clause
I want to execute the following SQL 我想执行以下SQL
select count(*) as myCount from user group by name;
I came up with the following criteria for the same 我想出了同样的以下标准
DetachedCriteria.ForClass(typeof(UserDTO))
.setProjections(Projections.ProjectionList()
.Add(Projections.rowCount(),"myCount")
.Add(Projections.groupProperty("this.name"));
I get the result back as pair of the count and name,How can I get just the count from this. 我将结果作为计数和名称的对返回,我怎样才能从中获得计数。
You can use count distinct if there is only one group by column. 如果列中只有一个组,则可以使用count distinct。
HQL: HQL:
select count(distinct name) as myCount from user
Criteria: 标准:
DetachedCriteria.ForClass(typeof(UserDTO))
.setProjections(Projections.ProjectionList()
.Add(Projections.countDistinct("name"),"myCount"));
I don't think you can do it with Criteria, but it's easy with HQL. 我不认为你能用Criteria做到这一点,但是用HQL很容易。 It's exactly the same string as your SQL query, but with entity/property names instead of table/column ones. 它与您的SQL查询完全相同,但使用实体/属性名称而不是表/列名称。
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