12 | Database Explorer fields can be edited using the following commands: The Edit > Set Reference > Set to Null command is used to set a reference to null. The Edit > Set Reference > Set to Existing Entity... command is used ... a reference field sets the value to null without deleting any referenced entity object |
10 | JPA Entity Fields. When an entity object is stored in the database every persistent field must contain either null or a value ... is persistable (or null). Every persistent field can be marked with one of the following annotations ... behavior. null values are allowed by default. Specifying optional=false (as demonstrated for field1 |
10 | FROM clause (JPQL / Criteria API) have any matching inner value it gets at least a NULL value as a matching value in the FROM iteration. Therefore, a Country c with no Capital city has a minimum representation of (c, NULL) in the FROM ... , the OUTER JOIN variant returns Nauru with a NULL value as its capital. [LEFT [OUTER] | INNER] JOIN |
10 | Paths and Types in JPQL and Criteria API through a NULL value The following query retrieves country names with their capital city names: SELECT ... is evaluated to NULL and c.capital.name is an attempt to navigate from a NULL value. In Java, a NullPointerException is thrown on any attempt to access a field or a method via a null reference. In JPQL |
9 | Database Schema Evolution with default values (0, false or null). Fields in the old schema that do not have matching fields in the new ... with a default value (0, false or null). The following type conversions are supported: From any numeric type ... that are stored as numeric ordinal values (the default). From any type to Boolean or boolean (0, null |
8 | javax.persistence.criteria.CriteriaBuilder an expression that returns null if all its arguments evaluate to null, and the value of the first non-null argument otherwise. Create an expression that returns null if all its arguments evaluate to null, and the value of the first non-null argument otherwise. Parameters: x - expression y - value Returns |
7 | Index Definition. When an entity object is stored in the database every indexed field must contain either null or ... . Arrays and collections that contain values of the above types (including null). Indexes |
7 | Retrieving JPA Entity Objects null is returned. A similar method, getReference, can be considered the lazy version of find ... might be returned (null is never returned). A hollow object is initialized with the valid primary |
1 | [ODB1] Chapter 6 - Persistent Objects strings). If getObjectID(...) is called with a transient parameter, it returns null. If it is called ... . Therefore, a null value can also be specified, but in order to keep the application JDO portable, a proper ... yet (and may be seen as null values in the debugger). When an access to another persistent object is made, the object |
0 | [ODB1] Chapter 9 - ObjectDB Explorer to set a reference field to a new object, to an exiting object or to null. You can add objects or ... " command changes according to the context. Deleting a reference field sets the value to null |
