hql application

1. HQL IntroductionHQL is an object-oriented query language, compared with the SQL query language, although syntactically similar, are run-time parsing, but HQL is not like SQL, such as data tables, columns and other database objects, HQL objects are classes, objects, properties and so on. It can also support inheritance and polymorphism, and

Hibernate hql syntax and related foreign key Association Hql For example, for the Tuser class 1. Object QueryString hql = "from user "; Executing this statement will return records of the user and the user subclass.Note: If the Tuser class has a foreign key, no error will be reported in the query results. However, if the foreign key in the results is null, a null

Hibernate -- HQL, QBC retrieval method, hqlqbc I. HQL Retrieval Method Test the HQL retrieval method using a bidirectional one-to-multiple method. Take Department and Employee as examples. Table creation statement: CREATE TABLE department( dept_id INT(11) PRIMARY KEY NOT NULL AUTO_INCREMENT, dept_name VARCHAR(50));CREATE INDEX FK_8hf3vewo7w3v9doungcc51wwy O

Background Based on the previous section, Hibernate (12): HQL query (i), we have learned a part about the use of HQL: HQL with parameter query HQL ORDER by Sort query HQL setting entity parameter queries This section will learn

Tags: parameter multi-table query string technology share create EXEC field tools factorHQL is an object-oriented query, format: from + Class name + Class object + where + object properties SQL is database-oriented table query, format: from + table name + where + table field1. EnquiryIt is recommended to use HQL (Hibernate query Language) to query statements when using queries in Hibernate. When using HQL y

Tags: query statement conditional query BSP change based on contrast application IV SelectI. Definition of JPQLIn Java EE, JPQL (Java Persistence Query Language) is designed specifically for Java applications to access and navigate entity instances. JPQL is an extension of the query language EJB QL used by EJB2, which inherits the EJB QL and makes some changes to it.Second, JPQL and SQLPQL is an object-oriented query language, so it can fully understa

SQL: Full-Name Structured Query Language (structured Query Language), a special purpose programming language, is a database query and programming language for accessing data and querying, updating and managing relational database systems , and is also the extension of the database script file. HQL: HQL (Hibernate query Language) query provides richer and more flexible query properties than the criteria quer

Overview Hibernate provides the following ways to retrieve objects1) The Navigation object graph retrieves the way: navigates to other objects according to the already loaded object;2)oid Retrieval Method: The object is retrieved according to the OID of the object;3)hql retrieval Method: Using object-oriented HQL query language;4)QBC Retrieval method: Use the QBC (Query by Criteria) API to retrieve the

1. Hibernate Query Introduction Hibernate hql Query, criteria query, call stored procedure Hibernate transaction management and concurrency control Hibernate delay loading strategy, crawl strategy, level two cache management Hibernate consolidation Struts 2. HQL Introduction hql:hibernate Query Language , which is an object-oriented query Language provided by Hibernate. (1) Set various query conditions in t

The content of this section Query methods in the NHibernate NHibernate Query Language (HQL) 1.from clause 2.select clause 3.where clause 4.order BY clause 5.group BY clause Example analysis Conclusion In the previous section, we initially set up a nhibernate program, completed mapping the Customer table and read the data function, this section and the next section we discuss the query method in the N

Hibernate-based Hibernate query language (hql) HqlKeywords in hql are case-insensitive, but attributes and class names are case-sensitive.1. Simple attribute Query [important]* For a single attribute query, a list of returned result set attributes is returned. The element type is consistent with the corresponding attribute type in the object class.* When querying multiple attributes, the returned collectio

Let's summarize the common syntax of the HQL statement: FROM clause:; Select clause: Used to select objects and attributes; WHERE clause: The restriction condition used to express the query statement; Use an expression: generally used in the WHERE clause; ORDER BY clause: used for sorting; Here is a summary of the HQL query based on a table of one of my projects:

Basic usage of hql 1. Object QueryString hql = "from Tuser "; Executing this statement will return records of Tuser and Tuser sub-classes. Hql = "from Java. Lang. Object"Records of all database tables in the database are returned. Where statementHql = "from Tuser as user where user. Name = 'yyy '"; The same can be omitted for.Hql = "from Tuser user where user. Na

Operators yesterday to ask a question, the table's fuzzy query only support the current page, the query needs a page page of the turn, the user experience needs to be improved. The technical level is because the query invokes the public pagination Pagequery (final criterion[] criterions, final integer startLine, final integer PageS ize, Final String by, final Boolean Isasc) {} method, which is good for single table query support, adding query conditions to criterion array, executing pagequery c

Hibernate is primarily a framework for interacting with databases, and you want to manipulate relational databases in an object-oriented language, as in the next two ways:HQL Statement : Object-oriented Query language, object names are case-sensitive. And unlike SQL, this is where the object is queried, not the table, and polymorphism is supported. HQL mainly through the query operationCriteria Class : is an object-oriented query, the main query crite

First, batch processing operationsBulk processing of data is the processing of large amounts of data in a transactional scenario. In applications where bulk operations are difficult to avoid,Hibernate provides the following ways to process data in batches:(1) Use HQL The database level for bulk operations(2) Use JDBC API for bulk operations database level(3) Use Session for batch operations will go into cache1. using

The previous article briefly introduced HQL it as Hibernate query language, encapsulated the basic SQL of all query operations, HQL can implement the database file additions and deletions, this article focuses on HQL entity object Query method.first, the Entity object queryEntity object queries are the basis of HQL que

In the integration process of SSH framework, novice will often encounter this problem. When we use the HQL statement query, the console error: XXX is not mapped. And at this time, many feel good English students will be dizzy. It then starts by checking that the mapping file for the entity class is *.hbm.xml correct, adding the mapping file to the spring configuration file, and so on. Then highlight a pass, still not effective.Let's get down to the ch

1. Unable to locate appropriate constructor on class .... Similar to "select new uservo (U. ID, U. Name) from user u where u. ID> 100" In this case, uservo must have a constructor that matches the (ID, name) type. 2. Like Fuzzy match: View plaincopy to clipboardprint? Public list String hql = "select * from user u where u. name like? " List Return result; } Public list Note that "%" is passed in as a parameter rather than directly spelled i

) {Session=sf.opensession (); Threadlocal.set (session); } returnsession; } Public Static voidSave (Object obj) {Session session=opensession (); Transaction TX=NULL; Try{TX=session.begintransaction (); Session.save (obj); Tx.commit (); } Catch(Exception e) {if(tx! =NULL) {tx.rollback (); } Throw Newruntimeexception (E.getmessage ()); } finally { if(Session! =NULLSession.isopen ()) {Session.close (); }}} @SuppressWarnings ("Unch