org.datanucleus.query

Class JPQLSingleStringParser

java.lang.Object

org.datanucleus.query.JPQLSingleStringParser

public class JPQLSingleStringParser
extends Object

Parser for handling JPQL Single-String queries. Takes a JPQLQuery and the query string and parses it into its constituent parts, updating the JPQLQuery accordingly with the result that, after calling the parse() method, the JPQLQuery is populated.

 SELECT [{result} ]
        [FROM {from-clause} ]
        [WHERE {filter}]
        [GROUP BY {grouping-clause} ]
        [HAVING {having-clause} ]
        [ORDER BY {ordering-clause}]
        [RANGE x,y]
 e.g SELECT c FROM Customer c INNER JOIN c.orders o WHERE c.status = 1
 

or

 UPDATE {update-clause}
 WHERE {filter}
 

and update-clause is of the form "Entity [[AS] identifier] SET {field = new_value}, ..." or

 DELETE {delete-clause}
 WHERE {filter}
 

and delete-clause is of the form "FROM Entity [[AS] identifier]"

Note that only the {filter} and {having-clause} can strictly contain subqueries in JPQL, hence containing keywords

 SELECT c FROM Customer c WHERE NOT EXISTS (SELECT o1 FROM c.orders o1)
 

So the "filter" for the outer query is "NOT EXISTS (SELECT o1 FROM c.orders o1)". Note also that we allow subqueries in {result}, {from}, and {having} clauses as well (vendor extension). If a subquery is contained we extract the subquery and then set it as a variable in the symbol table, and add the subquery separately. Note that the

[RANGE x,y]

is a DataNucleus extension syntax to allow for specification of firstResult/maxResults in the query string and hence in subqueries and is dependent on enabling datanucleus.query.jpql.allowRange.

Constructor Summary

Constructors

Constructor and Description
JPQLSingleStringParser(Query query, String queryString) Constructor for the Single-String parser.

Method Summary

Modifier and Type	Method and Description
JPQLSingleStringParser	allowRange()
void	parse() Method to parse the Single-String query

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

JPQLSingleStringParser

public JPQLSingleStringParser(Query query,
                              String queryString)

Constructor for the Single-String parser.

Parameters:

query - The query into which we populate the components of the query

queryString - The Single-String query

Method Detail

allowRange

public JPQLSingleStringParser allowRange()

parse

public void parse()

Method to parse the Single-String query