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1-50 of 200 resultsFROM clause (JPQL / Criteria API) The FROM clause declares query identification variables that represent iteration over objects in ... are always polymorphic. JPQL does not provide a way to exclude descendant classes from iteration at the FROM clause level. JPA 2, however, adds support for filtering instances of specific types | |
Criteria Query From Elements The interfaces in this group are in use for setting a criteria query FROM clause. Criteria Query Variables The FROM clause in JPA queries (as in SQL) defines the query variables. Query variables are represented in criteria queries by descendant interfaces of the From interface: Range | |
javax.persistence.criteria.From JPA Interface From Type Parameters: - the source type - the target type Super Interfaces: Expression , FetchParent , Path Represents a bound type, usually an entity that appears in the from clause, but may also be an embeddable belonging to an entity in the from clause. Serves as a factory | |
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CriteriaBuilder.substring(x,from,len) - JPA Method JPA Method in javax.persistence.criteria.CriteriaBuilder Expression substring ( Expression x, Expression from , Expression len ... at the specified position. First position is 1. Parameters: x - string expression from - start position | |
CriteriaBuilder.substring(x,from) - JPA Method JPA Method in javax.persistence.criteria.CriteriaBuilder Expression substring ( Expression x, Expression from ) Create an expression for substring ... position is 1. Parameters: x - string expression from - start position expression Return: expression corresponding to substring extraction Since: JPA 2.0 | |
CriteriaBuilder.substring(x,from) - JPA Method JPA Method in javax.persistence.criteria.CriteriaBuilder Expression substring ( Expression x, int from ) Create an expression for substring extraction ... is 1. Parameters: x - string expression from - start position Return: expression corresponding to substring extraction Since: JPA 2.0 | |
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CriteriaBuilder.locate(x,pattern,from) - JPA Method JPA Method in javax.persistence.criteria.CriteriaBuilder Expression locate ( Expression x, Expression pattern, Expression from ... for string to be located from - expression for position at which to start search Return: expression corresponding to position Since: JPA 2.0 | |
CriteriaBuilder.locate(x,pattern,from) - JPA Method JPA Method in javax.persistence.criteria.CriteriaBuilder Expression locate ( Expression x, String pattern, int from ) Create ... is returned. Parameters: x - expression for string to be searched pattern - string to be located from | |
CriteriaBuilder.substring(x,from,len) - JPA Method JPA Method in javax.persistence.criteria.CriteriaBuilder Expression substring ( Expression x, int from , int len ) Create ... . First position is 1. Parameters: x - string expression from - start position len - length Return | |
CriteriaDelete.from(entity) - JPA Method JPA Method in javax.persistence.criteria.CriteriaDelete Root from ( EntityType entity ) Create and add a query root corresponding to the entity that is the target of the delete. A CriteriaDelete object has a single root, the entity that is being deleted. Parameters: entity | |
CriteriaDelete.from(entityClass) - JPA Method JPA Method in javax.persistence.criteria.CriteriaDelete Root from ( Class entityClass ) Create and add a query root corresponding to the entity that is the target of the delete. A CriteriaDelete object has a single root, the entity that is being deleted. Parameters: entityClass | |
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AbstractQuery.from(entity) - JPA Method JPA Method in javax.persistence.criteria.AbstractQuery Root from ( EntityType entity ) Create and add a query root corresponding to the given entity, forming a cartesian product with any existing roots. Parameters: entity - metamodel entity representing the entity of type X | |
AbstractQuery.from(entityClass) - JPA Method JPA Method in javax.persistence.criteria.AbstractQuery Root from ( Class entityClass ) Create and add a query root corresponding to the given entity, forming a cartesian product with any existing roots. Parameters: entityClass - the entity class Return: query root corresponding to the given entity Since: JPA 2.0 | |
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CriteriaUpdate.from(entity) - JPA Method JPA Method in javax.persistence.criteria.CriteriaUpdate Root from ( EntityType entity ) Create and add a query root corresponding to the entity that is the target of the update. A CriteriaUpdate object has a single root, the entity that is being updated. Parameters: entity | |
CriteriaUpdate.from(entityClass) - JPA Method JPA Method in javax.persistence.criteria.CriteriaUpdate Root from ( Class entityClass ) Create and add a query root corresponding to the entity that is the target of the update. A CriteriaUpdate object has a single root, the entity that is being updated. Parameters: entityClass | |
Retrieving JPA Entity Objects The Java Persistence API (JPA) provides various ways to retrieve objects from the database ... with data that is retrieved from the database (or from the L2 cache - if enabled). The new entity object ... is returned as is. Otherwise, the object data is retrieved from the database and a new managed entity object | |
SELECT clause (JPQL / Criteria API) = em. createQuery ("SELECT c FROM Country c", Country.class); List results = query. getResultList ... country names as String instances, rather than Country objects: SELECT c.name FROM Country AS c Using ... are extracted from (or projected out of) entity objects to form the query results. The results | |
Paths and Types in JPQL and Criteria API classes) are represented in JPQL by the following types of expressions: Variables - FROM ... are assigned as arguments. Path expressions that navigate from one object to another. Instances of user ... . For example, c.capital.name is a nested path expression that continues from the Capital entity object | |
ORDER BY clause (JPQL / Criteria API) is at least one million people, ordered by the country name: SELECT c.name FROM Country c WHERE c.population 1000000 ORDER BY c.name When an ORDER BY clause exists it is the last to be executed. First the FROM clause ... are ordered by evaluation of the ORDER BY expressions. Only expressions that are derived directly from | |
DELETE Queries in JPA/JPQL As explained in chapter 2 , entity objects can be deleted from the database by: Retrieving the entity objects into an EntityManager . Removing these objects from the EntityManager ... , which are used to retrieve data from the database, DELETE queries do not retrieve data from | |
WHERE clause (JPQL / Criteria API) The WHERE clause adds filtering capabilities to the FROM -SELECT structure. It is essential in any JPQL query that retrieves selective objects from the database. Out of the four optional clauses ... : SELECT c FROM Country c WHERE c.population :p The FROM clause of this query defines an iteration | |
GROUP BY and HAVING clauses clause in the query execution order is after the FROM and WHERE clauses, but before the SELECT ... ) that are generated by the FROM clause iteration and pass the WHERE clause filtering (if any ... .name, 1, 1) FROM Country c GROUP BY SUBSTRING(c.name, 1, 1); The FROM clause defines iteration | |
Database Schema Evolution from int to Date ) the fields are not considered as matching and the new field is initialized with a default value ( 0 , false or null ). The following type conversions are supported: From any numeric ... and enum values that are stored as numeric ordinal values (the default). From any type to Boolean or | |
JPA Query Structure (JPQL / Criteria) rather than just field values from database tables, as with SQL. That makes JPQL more object oriented friendly ... ;of up to 6 clauses in the following format: SELECT ... FROM ... [WHERE ...] [GROUP BY ... [HAVING ...]] [ORDER BY ...] The first two clauses, SELECT and FROM are required in every retrieval query | |
Strings in JPQL and Criteria Queries is not found. The third argument (when present) specifies from which position to start the search. LOWER ... Characters The TRIM([[LEADING|TRAILING|BOTH] [char] FROM ] str) function returns a string after removing ... to 'UK' . TRIM(LEADING FROM ' UK ') is evaluated to 'UK ' . TRIM(TRAILING FROM ' UK ') is evaluated | |
JPA Persistable Types only once even if they are referenced multiple times. Referencing instances of other persistable types from ... . In most cases ObjectDB can overcome a missing no-arg constructor. Aside from these constraints ... , byte , short , char , int , long , float and double . Equivalent wrapper classes from package java | |
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