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What are the disadvantages of object-relational mapping ORM? Many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can gain something.

Object-relational mapping (ORM) provides conceptual and easy-to-understand methods for modeling data. The ORM methodology is based on three core principles: simplicity-modeling data in the most basic form; accessibility-database structures are documented in a language that anyone can understand; and accuracy-creating correct standardized structures based on data models. Modelers develop information models by collecting information from data modelers who are familiar with the application but are not skilled at it. Modelers must be able to communicate with data structures at the conceptual level in terms that non-technical enterprise experts can understand. The modeler must also be able to analyze the information in simple units and process the sample data. ORM is specifically designed to improve this connection.

ORM is based on three core principles:

Simplicity: model data in the most basic form. (a persistent class corresponds to a table, each instance of the class corresponds to a record in the table, and each property of the class corresponds to each field of the table. )

Accessibility: the database structure is documented in a language that anyone can understand.

Accuracy: create the correct standardized structure based on the data model.

ORM also has some shortcomings, as follows:

1. The execution efficiency is low. Automatic mapping of relational databases needs to consume system performance, and the execution efficiency is lower than that of SQL statements written directly.

2. It is not flexible enough, and ORM is not up to its goals for complex queries.

3. It is very possible to extract all the data into memory objects and persist all attributes, which will consume more memory space.

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