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Object as parameter results in exception

Object as parameter results in exception

CRUD Database Operations with JPA

. The getSingleResult method executes the query and returns the result. It should only be used when exactly one result value is expected (a single Long object in the query above). Let's see another example of a query that returns a single result: Query q2 = em.createQuery("SELECT AVG(p.x) FROM

FROM clause (JPQL / Criteria API)

pair of countries that do not share a border, returning as results only neighboring countries ... capital) is not part of any iterated pair and is therefore excluded from the query results. INNER JOIN ... and result iteration: TypedQuery<Country> query =       em.createQuery("SELECT c FROM Country c


should be used mainly when the query result type is unknown or when a query returns polymorphic results and the lowest known common denominator of all the result objects is Object. When a more specific result type is expected queries should usually use the TypedQuery interface. It is easier to run

Database Management Settings

" synchronized="false" />   <index-update enabled="true" priority="40" /> <query-cache results ... to accelerate the execution of relevant queries. The <query-cache> element <query-cache results="32mb ... that ObjectDB manages for queries: The results attribute specifies the size of the query result cache. Caching

Logical Operators in JPQL and Criteria API

the result is FALSE, because one FALSE operand is sufficient for a FALSE result. If one operand is NULL and the other operand is either TRUE or NULL, the result is NULL (unknown). ObjectDB supports the Java ... NULL represents unknown. Therefore, if one operand is NULL and the other operand is TRUE the result


> distinct(boolean distinct) Specify whether duplicate query results will be eliminated. Specify whether duplicate query results will be eliminated. A true value will cause duplicates to be eliminated ... results must be retained. Parameters: distinct - boolean value specifying whether duplicate results

Database Explorer

of elements. Use the [First] and [Max] fields to set the result range. Check [Disable Cache] to bypass query program and result caches. Click the Execute button to run the query. If the query is valid, a default viewer (a Tree window by default) is opened with the query results, and the size of the result

ObjectDB Object Database Features

optimized code (as a result of many profiling sessions). Unique data structures and algorithms (as a result of years of R&D). Outperforms competing products. Connection Pooling Automatic connection pool ... result cache (for repeating queries with the same arguments). Many other internal caches. Indexing


. There are three required elements in a Query: the class of the results, the candidate collection ... , import statements, ordering and grouping specifications, result and result class, the range of results, and flags indicating whether the query result is unique and whether the query can be modified

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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