Hql query:
Criteria queries encapsulate the query conditions in an object-oriented manner and conform to the programming mindset. However, hql (Hibernate query language) queries provide richer and more flexible query features, therefore, Hibernate
1. Object Query:The object query technology has already been involved many times before, for example, the following example:String hql = "from user ";List list = session. createquery (hql). List ();The code above is executed to query all the data
In the previous article we have mastered the basic data curd method, but in more cases, due to the differences in business logic, curd operations are often not so simple, especially complex business logic below, this is the ActiveRecord mode of
1, Entity query:As for the entity query technology, we have already dealt with it many times before, such as the following example:String hql= "from user User";List list=session. CreateQuery (HQL). List ();The result of the above code execution is
1, Entity query:As for the entity query technology, we have already dealt with it many times before, such as the following example:String hql= "from user User";List list=session. CreateQuery (HQL). List ();The result of the above code execution is
thinkphp query Language with coherent operation can be very good to solve the complex business logic requirements, this article we first to in-depth understanding of the framework of the query language.
1. Query Language Introduction
thinkphp
In the previous article, we learned the basic data CURD method, but in more cases, due to the difference in business logic, CURD operations are often not that simple, especially under complicated business logic, this is also a shortcoming of the
The most common update syntax is:
Update Set =,
Set =If my updated value is taken out of a SELECT statement and there are many columns, It is very troublesome to use this syntax.First, you need to select and place it on a temporary variable.
1.0 Introduction
The task of the Query planner is to find the best algorithm or to say "query plan" to complete an SQL statement. As early as SQLite version 3.8.0, the component of the query planner has been rewritten so that it can run faster and
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