Understanding of ORM

Orm has three main files:

1. Database Configuration File

2. ing File

3. Business Object files

 

Features of ORM:

1. no or few pre-compiled data accessCode

2. The data access code is dynamically generated through reflection during running (the ing between the business object class and the database object is obtained by reflecting the Business Object Class and parsing the ing file)

 

Disadvantages of ORM:

1. Low performance (because the use of reflection to dynamically generate data access code at runtime must be less efficient than the use of pre-compiled data access code)

2. Have a sufficient understanding of complex queries and do not have the necessary power

 

LINQ and ORM:

Language Integrated Query is a new language feature provided by. NET Framework 3.0. It is used for set-based operations. It has many implementations, also known as LINQ provider, which are the executors of LINQ queries, including LINQ to SQL, LINQ to object, LINQ to XML, LINQ to nhibties, and LINQ to entities.

Among them, LINQ to SQL is. net Framework 3.5 provides a lightweight ORM solution. Only it is related to Orm, and there is no relationship between other and Orm. Both of them are completely two technical concepts.

Orm composition:

1. A group of APIs that perform crud operations on persistent classes

2. Languages or APIs used to specify queries related to classes and class attributes

3. Tools for ing with metadata

4. Allows ORM implementation and dirty data check with transaction objects, lazy Association reading and other optimization technologies