hql requirements

The first contact with Hibernate was in 2004, when with a disturbed and uneasy mood to learn this technology. After several years of use and research, but also accumulated some experience, the following HQL and QBC query to talk about my work from some of the summary. This article will not talk about what is hibernate, what is ORM, and how to use HQL and QBC. The purpose of this article is to make everyone

against the T_user table tables, querying the name, age, and user_id three data columns;The second statement is used to execute a query against the user entity, querying the name, age, and UserId properties of the user entity.Third, HQLHQL (Hibernate query Language) is an object-oriented query, followed by a "table name", where the condition is followed by "fields in the table." When you use queries in Hibernate,Generally use HQL query statements. Be

Tags: size table standard different for conversion sharing LIS styleBecause HQL is object-oriented, so the use of HQL in statistical data is inappropriate, in fact HQL will eventually be converted into SQL statements, the project uses HQL statements should be standardized. Statistical data: The same table, the same fie

Use the HQL in NHibernate to query the data.Code:1 /// 2 /// Find Events 3 /// 4 Private void Btn_select_click (object sender, EventArgs e)5 { 6 7 }1. Query, and use parameters:1 //* * * Query * * *2IQuery query = session. CreateQuery ("From person p where p.id =? and P.name =: Name");3 4 //using parameters in NHibernate5 //one is "?" and one uses ":". If you use? ,

HQL syntax is based on sqlline(http://sqlline.sourceforge.net/), the DDL mainly contains database, function, view creation, modification, deletion, reference : ( Https://cwiki.apache.org/confluence/display/Hive/LanguageManual+DDL), syntax keywords: CREATE Database/schema, TABLE, VIEW, FUNCTION, INDEX DROP Database/schema, TABLE, VIEW, INDEX ALTER Database/schema, TABLE, VIEW SHOW Databases/schemas, TABLES, tblproperties, partition

HQL statementsString hql = "from the Song where name like '%" +text+ "% ' or singer like '%" +text+ "% ' or alumn like '%" +text+ "% '";Go heavy. Overrides Equals and Hascode of the Pojo class.@Overridepublic int hashcode () {TODO auto-generated Method Stubreturn 1;}@Overridepublic boolean equals (Object obj) {if (obj instanceof Song) {Song song = (song) obj;if (This.id.equals (Song.getid ())) {return true;

HQL Original from : http://slaytanic.blog.51cto.com/2057708/782175/ slaytanic teacherabout the Hadoop the introduction from:http://www.cnblogs.com/shishanyuan/p/4629300.html mountain Garden teacher , his Hadoop blog is well written, interested can go to seeHive is a Hadoop-based query tool for Facebook's open source, meaning that if you need hive, you'll install Hadoop first.The ecosystem of Hadoop is roughly as follows:The basic component of the L-hd

1. Find (string querystring ); Example: This. gethibernatetemplate (). Find ("from bean. User "); Returns all user objects. 2. Find (string querystring, object value ); Example: This. gethibernatetemplate (). Find ("from bean. User u where u. Name = ?", "Test "); Or fuzzy query: This. gethibernatetemplate (). Find ("from bean. User u where u. name like ?","% Test %"); Returns the object whose name attribute value is test (fuzzy query returns the object whose name attribute value cont

Hibernate query special characters such as % _ In SQL, %, _ and so on are special characters. Sometimes we need to query these special characters and escape them. The following two sentences are escaped. Select username from gg_user where username like '% Xiao/_ %' escape '/';Select username from gg_user where username like '% Xiao/%' escape '/'; The first SQL statement means that the _ after/is no longer used as a special character, and the second SQL statement means that the % after/is no long

Hql statements are designedUnderstanding of multi-state queries, From, followed by the persistence class name, not only query all instances of the persistence class, but also query all instances of the subclass of the class: From person as P This query statement not only queries all instances of the person, but also the child classes of the person, such as all instances of the teacher, provided that the person and teacher have completed the correc

1: Basic Query statementFrom is the simplest statement and the most basic HQL statement. The class name of the persisted class immediately after the FROM keyword.For example:From person indicates that all instances are selected from the person persistence class. Note that the entity class here is case sensitive! 2: Query part of fields to make new objectsSelect New article (a.id,a.title,a.category) from article a WHERE a.id =?Sometimes, you do not ne

I. Concept of nested subqueries:In SQL, a select-from-where statement becomes a query block. Nesting a query block in the WHERE clause of another query BlockIn a condition of a having phrase, such a query is called a nested query or a subquery. For example:From student sWhere S. SnO IN(Select SnO from SC where CNO = '1 ')The preceding hql statement generated in the hibernate background is:SelectStudent0 _. ID as id1 _,Student0 _. Sno as sno1 _,Student

The in condition is special. Besides using the setparameterlist method, the placeholder must be enclosed by "()". Otherwise, an error is returned. String hql ="Select P. querytemplate. ID, count (P. ID) from"+ Templateparameter. Class. getname ()+ "P where P. querytemplate. ID in (: idlist) group by P. querytemplate ";List result = Dao. Query (hql, "idlist", "1, 2, 3, 4, 6, 10, 11, 12,

Let the Framework do something to make SQL/hql/jdoql easier to write (on) This article discusses how to write the SQL processing layer that exists between common SQL/hql statements and JDBC/hibernate and contains hundreds of lines of code. In the open-source project, ibatis, an SQL-based ORM solution, can be referenced. In addition, it also has its new competitor orbroker, which is awesome and difficult to

When you write a HQL statement using Hibernate, I believe that there will be used to not equal to this condition, of course, most of them are used in the judgement is not equivalent to the case of empty strings, as for the HQL statement, in fact, and the general SQL statement does not make any difference, you can use!=, you can use the

We all know that it can be used in HQL. OR: * * * the way to configure query parameters externally, such as: Query query=session.createquery ("from Teststu s where S.team=:team and S.age>:age"); Or Query query=session.createquery ("from Teststu s where s.team=?") and S.age>?); From a persistent team object, take out the collection of Teststu it holds and filter out the records of age greater than the execution data We can set parameters like thisQ

We all know that you can use it in HQL. OR: * * * the way to configure query parameters externally, such as: Query query=session.createquery ("from Teststu s where S.team=:team and S.age>:age"); Or Query query=session.createquery ("from Teststu s where s.team=?") and S.age>?); The meaning of this sentence is to remove the Teststu collection from a persistent team object, and to filter out records of age greater than the execution data We can set t

(); } Catch(Exception ex) {MessageBox.Show (ex). Message); } } #endregion #region4.0 Execute HQL statement-private void Tsmiexecutehql_click (object sender, EventArgs e)Private voidTsmiexecutehql_click (Objectsender, EventArgs e) { stringSTRHQL ="From Student Stu where Stu. Id >:stuid"; IList"Stuid",7). List(); Dgvlist.datasource=stulist.tolist (); } #endregion #region5.0 executing

Here is a simple HQL statement, because a lot of more complex outside query, with the general query difficult to completeSo we need to use HQL here.@Testpublic void Selquery () {System.out.printf ("Hello"); Configuration config = new configuration (); Sessionfactory sessionfactory = config.configure ("Hibernate.cfg.xml"). Buildsessionfactory (); Session session = Sessionfactory.opensession (); Transaction

When using the HQL query in today's project, the Qingaocenterinfo is not mapped[from Qingaocenterinfo where ...] appears.There is obviously a problem with the hibernate mapping relationship.This exception occurs first to see whether the table name in the database table is used in the query statement, not the entity class.To view my code:Centerlist = Manager.find ("From Qingaocenterinfo center where center.type =?") and Center.centername =? ", new Obje