Makumba Specification

[JSP tag library: Intro | Listing | Forms]

Query languages

Hibernate HQL

OQL

The database can be interrogated using the following language ( [] means optional, {} means any number of repetitions). OQL is similar to SQL, a specification can be found at http://www.odmg.org (or check this PDF). Makumba recognizes a subset of OQL at the moment, which it translates to the host SQL when necessary.

SELECT expression [[AS] label] {, expression [[AS] label] }
FROM {type [AS] label | label.field{.field} [AS] label }
[   WHERE expression
    [    GROUP BY expression {,expression}
        [  HAVING expression {,expression}  ]
    ]
]
[ORDER BY expression {,expression} [(ASC|DESC)] ]

Notations like label.field{.field} only allow "field" to be of pointer type in expression and set type in FROM. In expressions, also label.ptr{.ptr}.simplefield is valid.

If a label, representing a type, appears alone in an expression, a default field will be added. The default field depends on the type of the label:

for set XXX types (sets of foreign objects), the label denotes the pointer to the set member
for set int { } and set char { } types, the label denotes the set member (i.e. and int or a string)
for all other types, the label denotes the pointer to that object

In OQL, NULL values are named 'nil', example

ms.account_active=1 OR ms.account_active=nil

In the future, the MDDs should use 'nil' instead of null, e.g. nickName = not nil char[20]

Hibernate Query Language - HQL

In the future, makumba will integrate Hibernate.
Doing so, you will be able to take full advantage of hibernate's query language HQL.