odata query

When you submit a query, MySQL will analyze it to see if some optimization can be done to make it faster to process the query. This section describes how the query optimizer works. If you want to know the optimization methods used by MySQL, you can refer to the MySQL reference manual. Of course, the MySQL query optimiz

Before introducing @query comments, let's look at how to use @namedquery for named queries 1. Now the definition method on the entity class has a specific query statement @Entity @NamedQuery (name = "Task.findbytaskname", query = "Select T from Task t where T.taskname =? 1") public Class task{ } 2. After we inherit the interface, we can use this method direct

Tags: MySQL query cache query Statement statistics Query Cache state interpretationAbout MySQL ' Show global status ' output of Com_select, Queries, Questions, Qcache_hits, Qcache_inserts, Qcache_not_ Cached these state values have been a bit confusing, now through the experiment to more accurate and profound understanding.Experiment version: 5.5.39The official e

I. Why should I enable this query? Databases are prone to bottlenecks. Now Nosql is so popular that it is estimated that they are all depressed by databases. The statements that affect the query speed in mysql are very slow. These slow statements may be written improperly or the Combined Query of multiple tables in big data, so we need to find out these words. I.

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

About MySQL lsquo; showglobalstatusrsquo; Output Com_select, Queries, Questions, Qcache_hits, Qcache_inserts, Qcache_not About MySQL lsquo; show global statusrsquo; Output Com_select, Queries, Questions, Qcache_hits, Qcache_inserts, Qcache_not The status values Com_select, Queries, Questions, Qcache_hits, Qcache_inserts, and Qcache_not_cached output by 'show global status' in MySQL have been somewhat confused, now we can learn more accurately and deeply through experiments. Lab version: 5.5

Crieria.uniqueresult (); Represents the result of a single fetchLazy load, do not load as long as it is not applicable (depending on the policy of the configuration file)Sometimes you want to overwrite the policy of the configuration file-------The introduction of the left connection Two retrieval statements are written to represent an and relationshipSQL1 and SQL2,Expression.eq equalsExpression.alleqEXPRESSION.GT Greater thanExpression.in needs a collection of Add (expression.in ())Set set =ne

Next: T-SQL Dynamic Query (1)--IntroductionObjective:In the development of features, we often encounter scenarios such as the following: The application has a query function that allows the user to select the desired condition in many query conditions. This is also the focus of this series.But sometimes you may find that some conditions are more or less mutually

Mysql uses indexes for query optimization and mysql index Query Optimization The purpose of indexing is to improve the query efficiency. It can be analogous to a dictionary. If you want to query the word "mysql", you must locate the m letter and find the y letter from the bottom down, find the remaining SQL. If there i

The HQL statement in Hibernate can basically implement what SQL statements do, just as jquery does for JavaScript. Although the HQL statement is the query of the class, but hql in the implementation of cluster query, group query, sorting and time of the poor query, do not need to q