hql requirements

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

In HQL, the requirements for the count () function are still strict. For example: 1. count (1) ErrorHql code "GetRecordCountById"> Select count (1) As recordCount from Km c Where c. id =: id 2. count (c. *) Error Hql code "GetRecordCountById"> Select count (c. *) as recordCount from Km c Where c. id =: id 3. The count (*) is correct.

Introduction and basic syntaxHql is case insensitive. When the same entity class name exists, use the package name. entity class.Query query = session. createquery ("from cat c ");List Returns a single object.Query q = session. createquery ("select count (c) from cat c ");Number num = (number) Q. uniqueresult (); // returns a single instanceInt COUNT = num. intvalue (); // return the value.When querying the total number of queries, the hql format must

HIBERNATE-HQL QueryHQL is the acronym for Hibernate Query Language, an object-oriented query language and the most common query language in hibernate.(i) Basic grammar of HQL Select "Property name" from "Object"where "condition"Group BY "attribute name" having "grouping condition"Order By "Property name" Desc/asc

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

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

The difference between 1.HQL and SQLSQL database-oriented table queryHQL Object-oriented queryHql:from followed by class name + Class object where to use the property of the object to do the conditionSql:from followed by the table name where to use the field in the table to make the conditionInquireWhen you use queries in Hibernate, you typically use HQL query statements.HQL (Hibernate query Language), Hibe

1./** * Query admin, query.list ()*/@Test Public voidEG1 () {Session session=NULL; Try{//Create sessionSession =hibernateutil.getsessionfactory (). Opensession (); //declares a variable and initializesString HQL ="From Admin"; //building a Query objectQuery query =session.createquery (HQL); //Execute QueryListquery.list (); //Traverse and output results for(Admin admin:adminlist) {System. out. p

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

HQL QueryHQL provides a very powerful feature, which is for persistent objects, with the acquisition of objects, without update,delete and insert operations. And the HQL is object-oriented, with inheritance, polymorphism and correlation characteristics. fromclause:The FROM clause is the simplest hql, such as from Student, and can also be written as select S from

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Transferred from: http://www.cnblogs.com/AnswerTheQuestion/p/6512701.htmlThis essay will document Hql's frequently used query statements to facilitate future viewing.Here by defining three classes, special, classroom, student to do the test, special and classroom is a one-to-many, classroom and student is a one-to-many relationship, here just paste the property code of these three beans:Special Class:public class special{ private int id; Private String name; Private String type; Priv

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: