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211

Date and Time in JPQL and Criteria Queries

Date and time expressions may appear in JPQL queries: as date and time literals - e.g. {d '2011-12 ... expressions - in navigation to persistent date and time fields. as results of predefined JPQL current date and time functions. Current Date and Time JPA defines special JPQL expressions
211

Collections in JPQL and Criteria Queries

Collections may appear in JPQL queries: as parameters - when collections are assigned as arguments ... enables as an extension to standard JPQL to use both operators (IN and MEMBER OF) with any type ... Expressions JPQL collection operators and functions (which are described above) are available also as JPA
211

Strings in JPQL and Criteria Queries

String values may appear in JPQL queries in various forms: as string literals - e.g. 'abc', ''. as ... to persistent string fields. as results of predefined JPQL string manipulation functions. LIKE - String ... operator). Criteria Query String Expressions JPQL string operators and functions (which are described
211

Paths and Types in JPQL and Criteria API

classes) are represented in JPQL by the following types of expressions: Variables - FROM ... . But more often they are used in JPQL path expressions that navigate to values of simple types (number, boolean ... , a NullPointerException is thrown on any attempt to access a field or a method via a null reference. In JPQL
207

Numbers in JPQL and Criteria Queries

Numeric values may appear in JPQL queries in many forms: as numeric literals - e.g. 123, -12.5. as parameters - when numeric values are assigned as arguments. as path expressions - in navigation ... of any type and always returns a double value. Criteria Query Arithmetic Expressions JPQL arithmetic
201

UPDATE SET Queries in JPA/JPQL

Existing entity objects can be updated, as explained in chapter 2, by: Retrieving the entity objects into an EntityManager. Updating the relevant entity object fields within an active transaction. Applying changes to the database by calling the commit method. JPQL UPDATE queries provide
201

DELETE Queries in JPA/JPQL

. Applying changes to the database by calling the commit method. JPQL DELETE queries provide
188

JPA Annotations for JPQL Queries

The following annotations are used to define static named JPA queries: The JPA Named Queries section of the ObjectDB Manual explains and demonstrates how to use these annotations to define named JPQL queries.
51

GROUP BY and HAVING clauses

The GROUP BY clause enables grouping of query results. A JPQL query with a GROUP BY clause returns ... clause. When a GROUP BY clause exists in a JPQL query, database objects (or tuples of database objects ... which returns the first letters as result. ObjectDB is very flexible in allowing JPQL expressions anywhere in
51

JPA Criteria API Queries

for building dynamic queries whose exact structure is only known at runtime. JPA Criteria API vs JPQL JPQL queries are defined as strings, similarly to SQL. JPA criteria queries, on the other hand ... rather than at runtime. On the other hand, for many developers string based JPQL queries, which are very similar to SQL

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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