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This article mainly introduces what type of database language sql is, and it has a certain reference value. Interested friends can refer to it. I hope you will gain a lot after reading this article.

Sql is a relational database language. Relational database language is a database language with multiple functions such as data manipulation and data definition. This language has the characteristics of interaction and can provide great convenience for users. Moreover, SQL language can be used to improve the quality and efficiency of computer application systems.

SQL belongs to the language of relational database

Relational database language is a database language with multiple functions such as data manipulation and data definition. This language has the characteristics of interaction and can provide great convenience for users. SQL language can also be used to improve the quality and efficiency of computer application systems.

Characteristics

1. Storage mode: the traditional relational database uses the table storage mode, and the data is stored in the way of rows and columns, which is very convenient to read and query.

2. Storage structure: relational database stores data according to a structured method. Each data table must define each field (that is, define the structure of the table first), and then store the data according to the structure of the table. The advantage of this is that the form and content of the data have been defined before the data is stored, so the reliability and stability of the whole data table are relatively high. But the problem is that once the data is stored, it will be very difficult to modify the structure of the data table.

3. Storage specification: in order to avoid repetition, standardize the data and make full use of the storage space, the relational database stores the data in the form of the minimum relational table, so that the data management can become very clear and clear at a glance. Of course, this is mainly the case of a data table. If it is multiple tables, the situation is different, because the data involves multiple data tables, there is a complex relationship between data tables, with the increase in the number of data tables, data management will become more and more complex.

4. Expansion mode: because the relational database stores the data in the data table, the bottleneck of data operation appears in the operation of multiple data tables, and the more data tables, the more serious the problem. If you want to alleviate this problem, you can only improve the processing ability, that is, to choose a faster and higher performance computer, although this method can expand the space to a certain extent, but the expansion space must be very limited. That is, relational databases only have the ability to scale up.

5, query method: relational database uses structured query language (SQL) to query the database. SQL has long been supported by various database manufacturers and has become the standard of the database industry. It can support the CRUD (add, query, update, delete) operation of the database, with very powerful functions. SQL can use similar index methods to speed up query operations.

6. Normalization: in the process of database design and development, developers are usually faced with the need to operate on one or more data entities (including arrays, lists and nested data) at the same time, so that in a relational database, a data entity is generally divided into multiple parts, and then the segmented parts are normalized, and then stored in multiple relational data tables. This is a complicated process. The good news is that with the development of software technology, quite a number of software development platforms provide some simple solutions, for example, the ORM layer (that is, object-relational mapping) can be used to map the object model in the database to the relational database based on SQL and to transform the data between different types of systems.

7. Transactionality: relational database emphasizes ACID rules (Atomicity, Consistency, Isolation, Durability), which can not only meet the requirements of transactional or complex data query, but also fully meet the requirements of high performance and operational stability of database operations. And the relational database emphasizes the strong consistency of data, and has a good support for the operation of transactions. Relational databases can control the atomicity and fine granularity of transactions and roll back transactions as soon as the operation is wrong or necessary.

8. Read and write performance: relational databases put great emphasis on data consistency, and pay a huge price for reducing read and write performance, although relational databases have good reliability in storing and processing data. However, once faced with massive data processing, the efficiency will become very poor, especially in the case of high concurrent read and write, the performance will decline very badly.

9. Authorization: Oracle,SQLServer,DB2,Mysql is common in relational databases. In addition to Mysql, most relational databases need to pay a high price if they want to use them. Even the free Mysql performance is subject to many restrictions.

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