Intersection of 2 expressions

Question

Hi,
I have a master-detail relation between 2 persistent classes. In java terminology, a master instance has a Collection of detail instances. I need to find master instances for which the collection contains detail 1 AND detail 2.
Example: Find all Employees having a Project with name="BigProject" AND a Project with budget="10000"
Note that the 2 conditions may be satisfied by 2 different projects. In other words, I don't mean "having a Project with (name="..." AND budget="...")
The following query pattern on the detail table returns the desired results :
SELECT DISTINCT <master id field>
FROM <detail table> t0
WHERE (t0.<field> = 'a value')
intersect
SELECT DISTINCT <master id field>
FROM <detail table> t0
WHERE (t0.<other field> = '<another value')
I don't know how to generate this, intersect is not in the Expression API.
Any ideas ?
JCG

Answer 1

Hi,
Here are some example expressions that I think will work:
ExpressionBuilder builder = new ExpressionBuilder(Employee.class);
Expression final =
builder.anyOf("projects").get("name").equal("BigProject").and(builder.anyOf
("projects".get("budget").equal("10000"));
This will return employees that have a Project named "BigProject" and a Project with budget "10000"
Another simliar expression:
Expression firstJoin = build.anyOf("projects");
Expression final = firstJoin.get("name").equal("BigProject").and(firstJoin.get("budget").equal("10000"));
This will return the employees who have a Project named "BigProject" with a budget of "10000". This is the situation you did not want.
Hope this helps.
Karen