criteria

Criteria Query通过面向对象的设计，将数据查询条件封装为一个对象。简单来说，Criteria Query可以看作是传统SQL的对象化表示，如： Criteria criteria=session.createCriteria(TUser.class); criteria.add(Expression.eq("name","Erica")); criteria.add(Expression.eq("sex",new Integer(1)); 这里的criteria实例本质上是对SQL“select * from t_user where name='Erica' and sex=1”的封装。 Hibernate在运行期会根据Criteria中指定的查询条件生成相应的SQL语句。 Criteria查询表达式 Criteria本身只是一个容器，具体的查询条件要通过Criteria.add方法添加到Criteria实例中。 方法 描述 Expression.eq 对应SQL “field=value”表达式 如：Expression.eq("name","Erica") Expression.allEq 参数为一个Map对象，其中包含了多个属性-值对应关系。相当于多个Expression.eq关系的叠加 Expression.gt 对应SQL“field>value”表达式

As my question states, I would like to know what we call types of queries with that type of condition in the WHERE clause, i.e.: SELECT * FROM mytable WHERE (col1, col2) < (1, 2); In other words: Give me all records where col1 is less than '1' or if it equals '1' then col2 must be less than '2' - and none of the values are NULL. I really like this type of syntax, but don't know what the naming convention is on how to refer to this type of condition. It looks like a tuple conditional but that name is not giving me anything from my searches. My question stems from needing to know what this

Is it possible to query "UNION" in JPA and even "Criteria Builder"? I'm looking for examples, but so far i got no result. Does anyone have any examples of how to use it? Or would that be with native sql? Masudul SQL supports UNION, but JPA 2.0 JPQL does not. Most unions can be done in terms of joins, but some can not, and some are more difficult to express using joins. EclipseLink supports UNION. Depending on the case, one could use sub queries, something like: select e from Entity e where e.id in ( select e.id from Entity2 e2 join e2.entity e where e2.someProperty = 'value' ) or e.id in (

Assuming the following scenario: class Project{ public Job Job; } class Job{ public Name; } Assuming I want to use the Criteria API to search for all projects whose Job has the name "sumthing". I could use the CreateAlias to create an alias for Job and use it to access Name, or I could create a new Criteria for the property Job and search by Name. Performance wise, is there any difference? Jaguar given these requirements there would be no difference, the generated SQL is the same: for mappings: <?xml version="1.0" encoding="utf-8" ?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">