ObjectDB Database Search

the call to getSingleResult in the same expression. Named parameters in a query string are identifiable by ... , parameters are defined implicitly when they appear in the query string. The parameter's type is inferred from the context. In the preceding example, comparing :name to a field of type String

Literals in JPQL, as in Java, represent constant values. JPQL supports various types of literals ... times with different parameter values. Embed literals in JPQL queries only when a single, constant ... , similar to null in Java and SQL. Because JPQL is case-insensitive, NULL , null , and Null

classes) are represented in JPQL by the following types of expressions: Variables : FROM ... persistent classes can participate in direct comparisons by using the = and operators. However, they are more often used in JPQL path expressions that navigate to values of simple types, such as

Collections can appear in JPQL queries in the following ways: As parameters when a collection ... (collection) function returns the number of elements in a specified collection. For example: SIZE(c.languages) returns the number of elements in the languages collection. [NOT] MEMBER [OF] The [NOT] MEMBER

String values can appear in JPQL queries in several forms: As string literals , for example, 'abc ... in an ESCAPE clause. For example: '100%' LIKE '%\%' ESCAPE '\' is evaluated to TRUE . '100' LIKE '%\%' ESCAPE '\' is evaluated to FALSE . In the preceding expressions, the first percent sign

Most JPQL queries use at least one comparison operator in their WHERE clause. Comparison operators ObjectDB supports two sets of comparison operators, as shown in the following table: Set 1: JPQL ... (the JDO Query Language). ObjectDB supports both forms. In addition to the different notation

Numeric values can appear in JPQL queries in several forms: As numeric literals , such as 123 ... ( % ) and bitwise complement ( ~ ) operators, which are supported in Java and JDO. JPA follows Java ... . The CriteriaBuilder interface provides factory methods for building these expressions, as shown in

Date and time expressions can appear in JPQL queries in the following ways: As date and time ... . Date and time in criteria queries The CriteriaBuilder interface provides three factory methods ... to reflect the current date and time. Functions for extracting date and time parts are also available in

Logical operators in JPQL and JPA criteria queries combine simple Boolean expressions to form complex expressions. Logical operators ObjectDB supports two sets of logical operators, as shown in ... for NOT . Criteria query logical operators Boolean expressions and predicates In criteria queries

As explained in Chapter 2 , you can delete entities from the database by following these steps ... that is cached in its persistence context. Therefore, using a separate EntityManager for DELETE queries ... + an optional variable ObjectDB supports using the java.lang.Object class in queries as an extension

You can update existing entities, as explained in chapter 2 , by following these steps: Retrieve ... specified entities directly in the database without retrieving them first. Using an UPDATE query ... , the EntityManager might not be aware that an UPDATE query has modified a cached entity in

Jakarta Persistence (JPA) Interface in jakarta.persistence.criteria.CriteriaBuilder jakarta.persistence.criteria.CriteriaBuilder. In Super Interfaces: Predicate , Expression , Selection , TupleElement Interface used to build in predicates. Since: Jakarta Persistence (JPA) 1.0 Public Instance

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.CriteriaBuilder In in (    Expression expression ) Create predicate to test whether given expression is contained in a list of values. Parameters: expression - to be tested against list of values Returns: in predicate. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.CriteriaBuilder. In In value (    T value ) Add to list of values to be tested against. Parameters: value - value Returns: in predicate. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.CriteriaBuilder. In In value (    Expression value ) Add to list of values to be tested against. Parameters: value - expression Returns: in predicate. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Enum Constant in jakarta.persistence.ParameterMode IN Stored procedure input parameter Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.CriteriaBuilder. In Expression getExpression() Return the expression to be tested against the list of values. Returns: expression. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.Expression Predicate in (    Object... values ) Create a predicate to test whether the expression is a member of the argument list. Parameters: values - values to be tested against Returns: predicate testing for membership. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.Expression Predicate in (    Expression ... values ) Create a predicate to test whether the expression is a member of the argument list. Parameters: values - expressions to be tested against Returns: predicate testing for membership. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.Expression Predicate in (    Collection values ) Create a predicate to test whether the expression is a member of the collection. Parameters: values - collection of values to be tested against Returns: predicate testing for membership. Since: Jakarta Persistence (JPA) 1.0

Jakarta Persistence (JPA) Method in jakarta.persistence.criteria.Expression Predicate in (    Expression values ) Create a predicate to test whether the expression is a member of the collection. Parameters: values - expression corresponding to collection to be tested against Returns

The ObjectDB Explorer is packaged in the explorer.jar executable file, which is located in the bin directory ... line as follows: $ java -jar explorer.jar If explorer.jar is not in the current directory ... a database connection To open a local database file in embedded mode, use the File Open Embedded... command

OF THIS AGREEMENT. 1. DEFINITIONS "Contribution" means: a) in the case of the initial Contributor, the initial code and documentation distributed under this Agreement, and b) in the case of each subsequent ... which: (i) are separate modules of software distributed in conjunction with the Program

, persistent, and inverse fields) can be used in both entity classes and embeddable classes . However, the last two groups (primary key and version fields) can be used only in entity classes. Primary key fields are discussed in the Primary Key section. Transient fields Transient entity fields are fields

Persistable types are data types that can be used for storing data in the database. ObjectDB ... can be stored directly in the database. Other persistable types can be embedded in entity classes as fields . In addition, only entity class instances preserve their identity and are stored

The FROM clause declares query identification variables for iterating over objects in the database. A query identification variable is similar to a variable in a Java enhanced for loop ... (you can use type expression to exclude descendant classes from iteration). For example, in

. The persistence context serves as a cache for retrieved entities. If a requested entity is not in ... uses the no-argument constructor. Therefore, you should avoid time-consuming operations in ... class is not an entity class. If the EntityManager already manages the specified entity in

to be enhanced. Enhancement improves efficiency in three ways: Enhanced code enables efficient tracking ... explained in Chapter 3 ). Special code is added to enhanced classes that automatically notifies ObjectDB ... ), but persistent fields that reference entities directly ( in a one-to-one relationship) must be loaded

the Service. By using the Service, You agree to the collection and use of information in accordance ... shall have the same meaning regardless of whether they appear in singular or in plural. Definitions ... ", "We", "Us" or "Our" in this Agreement) refers to ObjectDB Software Ltd, 109 Vernon House Friar Lane Unit 632

mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form

Using Jakarta Persistence (JPA) You can store new entities in the database either explicitly by ... code stores an Employee entity class instance in the database: Employee employee = new Employee ... , and changes its state to Managed. The new entity is stored in the database when the transaction

Querying without indexes requires sequential iteration over entities in the database. If many ... . However, index management introduces overhead in maintenance time and storage space. Therefore, you should choose ... , which prevents duplicate values in the indexed field. If you try to commit or flush a transaction

of the resulting groups instead of individual objects and fields. In the query execution order ... over all Country objects in the database. The GROUP BY clause groups these Country objects by the first ... the result. Although ObjectDB allows JPQL expressions almost anywhere in a query, the preceding query

Entities are in -memory instances of entity classes (persistable, user-defined classes) that represent physical objects in the database. Managing an ObjectDB database with JPA requires using entities ... . When an entity is first created, its state is New . In this state, the object is not yet associated

: In client-server mode, the ObjectDB server must be restarted after a schema change. Automatic ... happens automatically in memory each time the entity is loaded. The object in the database is updated to the new schema only when that entity is stored in the database again. An entity is converted

). @PostPersist : Invoked after a new entity is stored in the database (during a commit or flush operation ... is updated in the database (during a commit or flush operation). @PreRemove : Invoked when an entity ... annotation. By default, callback methods in a superclass are also invoked for entities of its subclasses

is essential to avoid update collisions when concurrent users simultaneously update the same data. In ... , it is easier to use and more efficient. In the rare cases where update collisions must be detected ... entity is 1 when it is first stored in the database. In every transaction where an entity 

expression in SELECT clauses. Specifying the required query results more precisely can improve ... must always be specified explicitly. JPQL does not support the the SELECT * expression, which is common in SQL ... c.name FROM Country AS c Using path expressions , such as c.name , in query results is called

over all Country objects in the database, using c as the range variable. Before passing these Country objects ... expression in the WHERE clause, also known as the predicate, determines which objects to accept ... between the FROM and SELECT clauses. In practice, if a suitable index is available , the database

Because an ObjectDB database is stored as a single file in the file system, you can back it up by ... it is not open in an ObjectDB server or in use by any application. ObjectDB also supports online backups, which let you back up a database while it is in use. This feature is useful for applications

;file to define a persistence unit. You can now define a persistence unit entirely in Java code ... ;file on the classpath. persistence.xml Persistence units are defined in a persistence.xml file, which must be located in the META-INF directory on the classpath. A single persistence.xml file

The ObjectDB Server is a tool that manages ObjectDB databases in a separate, dedicated process. This makes the databases accessible to client applications in other processes, including those on remote computers. The main benefits of running an ObjectDB server in client-server mode are: The ability

. The page attribute specifies the size of a page in a database file. The default value of 2 KB ... sync= "false" results in much faster database writes, but sync="true" is safer for production environments. By default, the recovery file is created in the same directory as the database file

, which was the only query interface in JPA 1, and the TypedQuery interface, which was introduced in JPA 2 ... interface makes it easier to run queries and process results in a type-safe manner. Building queries ... em in the following code snippets). The EntityManager serves as a factory for both Query

during their lifetime. For example, in a web application, it is common to establish a separate database ... rather than a persistence unit name. To use ObjectDB embedded directly in your application (embedded mode ... client-server mode, specify a URL in the format objectdb://host:port/path . In this case, an ObjectDB

all its EntityManager instances. The broader scope of this cache makes it useful in applications that use many short-term EntityManager instances. In addition to the EntityManager 's L1 cache ... : Globally in the ObjectDB configuration. Per persistence unit in the persistence.xml file

Every entity stored in the database has a primary key. Once assigned, the primary key cannot be modified and represents the entity for as long as it exists in the database. As an object database ... databases. Entity identification Every entity in the database is uniquely identified

) . getResultList (); You can invoke these methods in a single expression with getResultList because the setter methods in Query and TypedQuery support method chaining by returning the query object ... must be flushed to the database to be visible to the query. The flush policy in JPA is represented by

database is managed on multiple computers, or nodes, which can be in different geographic locations ... . In a master-slave replication model, the master node manages the primary database, which supports both read and write operations. The other nodes in the cluster, known as slave nodes, manage identical

ObjectDB can record its internal engine operations in special binary recording files (journal files). Recording is disabled by default and can be enabled in the configuration . The ObjectDB Replayer ... default, the recording directory is created in the same directory as the database file. If the purpose