Fast Object Database for Java - with JPA/JDO support


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GROUP BY and HAVING clauses

The GROUP BY clause enables grouping of query results. A JPQL query with a GROUP BY clause returns properties of generated groups instead of individual objects and fields. The position of a GROUP BY ... clause. When a GROUP BY clause exists in a JPQL query, database objects (or tuples of database objects

ORDER BY clause (JPQL / Criteria API)

expression: SELECT FROM Country c ORDER BY DESC Grouping (GROUP BY) Order The ORDER BY ... and a GROUP BY clause the SELECT clause receives groups rather than individual objects and ORDER BY ... WHERE 'Europe' MEMBER OF c.continents GROUP BY c.currency HAVING COUNT(c) > 1 ORDER BY c.currency

JPA Query Structure (JPQL / Criteria)

of up to 6 clauses in the following format: SELECT ... FROM ... [WHERE ...] [GROUP BY ... [HAVING ... (update and delete queries have a slightly different form). The other JPQL clauses, WHERE, GROUP BY ... GROUP BY / HAVING (groupBy, having, count, sum, avg, min, max, ...). Criteria ORDER BY (orderBy, Order, asc, desc).


Method javax.jdo.Query void setGrouping( String group ) Set the grouping expressions, optionally including a "having" clause. When grouping is specified, each result expression must either be an expression contained in the grouping, or an aggregate evaluated once per group. Parameters: group

Chapter 4 - JPA Queries (JPQL / Criteria)

(and a criteria query) is explained by describing the main clauses of JPQL queries (SELECT, FROM, WHERE, GROUP BY, HAVING, ORDER BY): Then the expressions that are used for building JPQL and criteria query

[ODB1] Chapter 4 - JDO Metadata

fetch group should include fields that are needed often and are relatively small. By default ... , arrays and references to user defined classes are excluded by default. The default-fetch-group attribute ... . The metadata is used first by the JDO Enhancer, and later by the JDO

Grouping by date()

have to group by date(). For few queries I was concatenating 'date' from year()-month()-day() calls ... . When you group by date() there are two days per day. I mean group by divides each day ... hour(ov.created), count(ov) from ObjectView ov group by hour(ov.created) order by hour(ov.created) ASC

Group by date / time

Hi, I'm trying to create reporting query that will return entities grouped by year / mont / day ... stats WHERE YEAR(record_date) = 2009 GROUP BY YEAR(record_date), MONTH(record_date) or maybe something like this: SELECT COUNT(id) FROM stats WHERE YEAR(record_date) = 2009 GROUP BY DATE

Step 1: Create a Maven Web Project

We start by creating a new Maven-WTP dynamic web project in Eclipse: Open the [New Project] dialog box, e.g. by using File > New > Project... Select Maven > Maven Project and click Next. Verify ... a filter, select maven-archetype-webapp in the artifact list and click Next. Enter Group Id (e.g

Group by: list if no aggregate function is specified

Hello! In a query like SELECT parent, children FROM Parent parent LEFT JOIN p.children children GROUP BY parent maybe it would be good if it will return a list of Object[2], where the second object is a list of children of a parent. Because creating a query to get a list of parents, then fetching

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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