Fast Object Database for Java - with JPA/JDO support

About GROUP BY

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424

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
181

ORDER BY clause (JPQL / Criteria API)

expression: SELECT c.name FROM Country c ORDER BY c.name 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
67

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).
61

setGrouping(group)

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
59

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
40

[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
32

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
32

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
32

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
31

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

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