SQL 使用 Hibernate 的标准和投影来选择多个不同的列
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Using Hibernate's Criteria and Projections to Select Multiple Distinct Columns
提问by bvulaj
Using Hibernate's Criteria, I want to execute the equivalent of:
使用 Hibernate 的标准，我想执行相当于：
select distinct uspscity, state from citycomplete where USPSCITY = 'HOUSTON'
I thought doing the following would yield the results I wanted:
我认为执行以下操作会产生我想要的结果：
ProjectionList projList = new ProjectionList();
projList.add(Projections.distinct(Projections.property("id.state")));
projList.add(Projections.distinct(Projections.property("id.uspsCity")));
criteria.setProjection(projList);
But, what this actually does is execute something like:
但是，这实际上是执行以下操作：
select distinct uspscity, distinct state from citycomplete where USPSCITY = 'HOUSTON'
Which throws an error, obviously.
显然，这会引发错误。
Other than not using Criteria, is there a solution for this?
除了不使用 Criteria 之外，还有其他解决方案吗？
Thanks,
谢谢，
Brandon
布兰登
回答by JB Nizet
ProjectionList projList = Projections.projectionList();
projList.add(Projections.property("id.state"));
projList.add(Projections.property("id.uspsCity"));
criteria.setProjection(Projections.distinct(projList));
