一.django自带的ORM中可以定义表与表之间的对应关系.现比较一下各个不同关系之间数据库端的实现 1.ForeignKey(ManyToOne)关系 from django.db import models # Create your models here. class User(models.Model): name=models.CharField(max_length=30) phoneNumber=models.BigIntegerField() class Blog(models…
To add a new app, first cd to the project. Then run: python manage.py startapp scrumboard After that a new folder call 'scrumboard' will be created in you applicaiton folder. Now cd to scrumboard folder and open models.py: from django.db import model…
Database and models The database Now that we have the Album module set up with controller action methods and view scripts, it is time to look at the model section of our application. Remember that the model is the part that deals with the application…
Database API Introduction Basic Usage Selects Joins Aggregates Raw Expressions Inserts Updates Deletes Unions Introduction An improved Database API was recently added, which includes a QueryBuilder and a simple but powerful Model. Everything regardin…
models templates models and databases models 如何理解models A model is the single, definitive source of information about your data. It contains the essential fields and behaviors of the data you’re storing. Generally, each model maps to a single databas…
Laravel Repository Pattern The Repository Pattern can be very helpful to you in order to keep your code a little cleaner and more readable. In fact, you don’t have to be using Laravel in order to use this particular design pattern. For this episode…
Performance Considerations for Entity Framework 5 By David Obando, Eric Dettinger and others Published: April 2012 1. Introduction Object-Relational Mapping frameworks are a convenient way to provide an abstraction for data access in an object-orient…
1.三种保护模式 – Maximum protection 在Maximum protection下, 可以保证从库和主库数据完全一样,做到zero data loss.事务同时在主从两边提交完成,才算事务完成.如果从库宕机或者网络出现问题,主从库不能通讯,主库也立即宕机.在这种方式下,具有最高的保护等级.但是这种模式对主库性能影响很大,要求高速的网络连接. – Maximum availability 在Maximum availability模式下,如果和从库的连接正常,运行方式等同Maxi…
Paginator There are several ways to paginate items. The simplest is by using the paginate method on the query builder. Paginating Database Results $users = DB::table('users')->paginate(15); The argument passed to the paginate method is the number of…
django操作多数据库 1. 添加数据库路由分配文件 在项目文件夹里创建‘database_router’文件.将下面的代码复制到该文件里. from django.conf import settings DATABASE_MAPPING = settings.DATABASE_APPS_MAPPING class DatabaseAppsRouter(object): """ A router to control all database operations…
