Fast Object Database for Java - with JPA/JDO support

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5

Performance issues on aggregate query

) from ObjectNode o INNER JOIN o.properties p1 INNER JOIN o.properties p2 INNER JOIN o.properties p3 INNER JOIN o.properties p4 INNER JOIN o.properties p5 INNER JOIN o.properties p6 INNER JOIN o.properties p7 join o.linkedObjects c1 where o.classIdentifier = '(OP)' and (o.linkedObjects
4

javax.persistence.JoinColumn

a column for joining an entity association or element collection. If the JoinColumn annotation itself is defaulted, a single join column is assumed and the default values apply. Example: @ManyToOne ... @JoinColumn(name="CUST_ID") // join column is in table for Order public Set
4

javax.persistence.MapKeyJoinColumn

) Specifies a mapping to an entity that is a map key. The map key join column is in the collection table, join table, or table of the target entity that is used to represent the map. If no MapKeyJoinColumn annotation is specified, a single join column is assumed and the default values apply. Example 1
3

JPA Queries

variables, join and fetch): Other criteria query expressions (for all the query clauses):
3

WHERE clause (JPQL / Criteria API)

language from a specified set of languages: SELECT c, l FROM Country c JOIN c.languages l WHERE c
3

UPDATE SET Queries in JPA/JPQL

variable name) for iteration. Multiple variables and JOIN are not supported. The SET clause defines one or
3

SELECT clause (JPQL / Criteria API)

can be added to the SELECT clause by using a bound JOIN variable in the FROM clause. Nested path expressions
3

DELETE Queries in JPA/JPQL

cannot include multiple variables and JOIN, and cannot include the GROUP BY, HAVING and ORDER BY clauses
3

JPA Criteria API Queries

, construct). FROM clause (from, join, fetch). WHERE clause (where). GROUP BY / HAVING clauses (groupBy
3

JPA Query Structure (JPQL / Criteria)

, array, tuple, construct). Criteria FROM (from, join, fetch). Criteria WHERE (where). Criteria

Getting Started

ObjectDB is very easy to use. Follow the Getting Started Tutorial and the Quick Tour manual chapter and in minutes you may be able to write and run first Java programs against ObjectDB.

Prior knowledge or experience in database programming (SQL, JDBC, ORM, JPA, etc.) is not required, but some background in using the Java language is essential.

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