15 | Paths and Types in JPQL and Criteria API classes) are represented in JPQL by the following types of expressions: Variables - FROM ... as arguments. Path expressions that navigate from one object to another. Instances of user defined ... . But more often they are used in JPQL path expressions that navigate to values of simple types (number, boolean |
14 | ORDER BY clause (JPQL / Criteria API) Expressions The following query returns names of countries whose population size ... . Then the SELECT clause builds the results by evaluating the result expressions. Finally the results are ordered by evaluation of the ORDER BY expressions. Only expressions that are derived directly |
14 | SELECT clause (JPQL / Criteria API) objects. JPA 2 adds the ability to use almost any valid JPQL expression in SELECT clauses ... - JPQL does not support the "SELECT *" expression (which is commonly used in SQL). Projection of Path Expressions JPQL queries can also return results that are not entity objects. For example |
13 | Date and Time in JPQL and Criteria QueriesDate 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 |
13 | Literals in JPQL and Criteria Queries The CriteriaBuilder interface provides two factory methods for building literal expressions. Ordinary Literals The main method, literal, takes a Java object and returns a literal expression. For example: // Boolean literals: Expression<Boolean> t = cb.literal(true); Expression<Boolean> f = cb |
13 | GROUP BY and HAVING clauses which returns the first letters as result. ObjectDB is very flexible in allowing JPQL expressions anywhere in ... . Only identification variables and path expressions are currently supported in the GROUP BY clause by ... of currencies that are in use by countries in that group. The DISTINCT keyword in a COUNT aggregate expression |
12 | Comparison in JPQL and Criteria API and expressions that include an unknown value are evaluated as unknown, i.e. to NULL. IS [NOT] NULL ... which are provided by JPQL (and SQL): c.president IS NULL c.president IS NOT NULL The expressions ... ) expressions: c.president == null c.president != null Comparable Data Types Comparison is supported |
11 | JPA Criteria API Queries, the range variable, c, is also used in the SELECT clause as the query result expression ... on how to set criteria query clauses and build criteria expressions. Running this query requires setting ... , including in the context of string based JPQL queries. Criteria Query Expressions JPA query clauses |
10 | Logical Operators in JPQL and Criteria API expressions out of simple JPQL boolean expressions. Logical Operators ObjectDB supports 2 sets ... part of its JDO support. Criteria Query Logical Operators Boolean Expressions and Predicates Boolean expressions are represented in criteria queries by Expression<Boolean> and descendant interfaces. For example |
9 | WHERE clause (JPQL / Criteria API) to function as a filter. The boolean expression in the WHERE clause, which is also known as the WHERE predicate, defines which objects to accept. Only Country objects for which the predicate expression ... Expressions in WHERE The above queries demonstrate only a small part of the full capabilities |
