About expression

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JPA Query Expressions (JPQL / Criteria)

Query expressions are the foundations on which JPQL and criteria queries are built. Every query ... of JPQL / Criteria query expressions. Atomic Expressions The atomic query expressions are: JPQL / Criteria Variables JPQL / Criteria Parameters JPQL / Criteria Literals Every query expression consists

Criteria Query Expressions

The following interfaces are in use in representing general expressions in criteria queries: See the Query Expressions section for more details and examples.

Numbers in JPQL and Criteria Queries

parameters - when numeric values are assigned as arguments. as path expressions - in navigation to persistent numeric fields. as aggregate expressions - e.g. COUNT. as collection functions ... .g. LOCATE, LENGTH. as composite arithmetic expressions that use operators and functions to combine

Strings in JPQL and Criteria Queries

parameters - when string values are assigned as arguments. as path expressions - in navigation ... for a match (usually a path expression) and the right operand is always the pattern (usually a parameter or ... '%\%' ESCAPE '\' is evaluated to FALSE. In the expressions above only the first percent character

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

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 the ORDER BY expressions. Only expressions that are derived

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 t = cb.literal(true); Expression f = cb


selections, expressions, predicates, orderings. Note that Predicate is used instead of Expression in ... . Expression abs( Expression x) Create an expression that returns the absolute value of its argument. Create an expression that returns the absolute value of its argument. Parameters: x

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

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 and descendant interfaces