Retrieving Records with Multiple keys. OPENJPA

Question

On the language that I know, RPG... You can use multiple keys and find retrieve the values of the record.

Like for table. I can select keys lolo and apple to retrieve the value of sex witch is F. Howerver I could not find some functionality that is like this in OPENJPA.. find() can only use one key? Is there something like find(names.class,:"LOLO","Apple") where keys are F_NAME and L_NAME?

Names
F_NAME   L_NAME   Sex
LOLO     Apple     F

Ben      Coke      M

While reading jpa, usually the table has P_ID

P_ID     F_NAME  L_NAME  Sex
1        LOLO     Apple   F 
2        Ben      Coke    M

To retrieve the record lolo apple, i need to use this code..

Names name = em.find(Names.class, 1);

How will you know the sex if the given value is F_NAME? and L_NAME? In SQL you can just say select * from Names where F_NAME = Lolo , L_NAME = "Apple" and it will output

P_ID     F_NAME  L_NAME  Sex
1        LOLO     Apple   F 

From that you can say that Sex = F. Like i want to know if lolo apple is male or female, I will search lolo apple on the database... not P_ID = 1. How would i konw what is the P_ID of Lolo Apple.

Hopefully you get what I mean.. Thanks.

Or maybe in another part of the equation, on JPA, how to you retrieve the record to be updated while not knowing yet the P_ID (Primary key) like you only know the first name and last name?

Answer 1

If you look at the OpenJPA documentation it defines a JPA Query Language [JPQL]. Wouldn't that be the place to start?

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UPDATE

If you want to specify several key values, why not just specify them in the WHERE clause in JPQL, like you would do in SQL.

SELECT ...
  WHERE colX = val1 and colY = val2 and colZ = val3