hadoop hql

HQL is short for Hibernate Query Language, that is, hibernate Query Language: HQL adopts the Object-Oriented Query Method. HQL queries provide more abundant and flexible query features. Therefore, Hibernate sets the HQL query method as the standard query method officially recommended.

As a veteran ORM framework, Hibernate's contribution to the database persistence layer is a visible achievement.It provides more and more data query methods, from SQL to self-created HQL to object-oriented standardized queries.Although the query is a bit confusing, the configuration is a bit more complicated to Use.But There's no way to hide its fascinating place, this blog tries to summarize all of Hibernate's Queries.Radish green vegetables each the

Content of this section The query method in nhib.pdf Hql) 1. From clause 2. Select clause 3. Where clause 4. Order by clause 5. Group by clause Instance analysis Conclusion In the previous section, we initially set up a Nhibernate program to map the customer table and read data. This section and the next section will be discussed inThe query method in nhib.pdf. Before that, I would like to recall what was completed in the pr

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

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

1. Find (String hql); General QueryExample: This.gethibernatetemplate (). Find ("from User");2. Find (String hql,object value);//A query conditionExample: This.gethibernatetemplate (). Find ("from User u where u.name=?", "Test");3. Find (String hql,object[] values);//Multiple query conditionsExample: This.gethibernatetemplate (). Find ("from User u where u.name=?

The previous article discussed in detail the HQL query in the Entity object query, and at the end of the simple introduction of SQL Native Query, HQL is the object query, so in the Query method and SQL may not be the same, in learning to use HQL only need to understand the different points, so you can quickly get started using

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

1. Non-integrated springHibernate's search method, mainly has the following five kinds.1. Navigation object Graph retrieval method. (Navigate to other objects based on the objects that have already been loaded.) ）2.OID retrieval method. (objects are retrieved according to the OID of the object.) ）3.HQL retrieval method. (Use the object-oriented HQL query language.) ）4.QBC retrieval method. (Use the QBC (Qur

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