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Today, I will talk to you about what is the acronym of data definition language, which may not be well understood by many people. in order to make you understand better, the editor has summarized the following for you. I hope you can get something from this article.

The abbreviation of data definition language is "DDL", and the English full name is "Data Definition Language". It is a language used to describe the real-world entities to be stored in the database, including structure definition, operation method definition and so on.

The acronym for data definition language is "DDL".

Database schema definition language DDL (Data Definition Language) is a language used to describe real-world entities to be stored in a database.

Brief introduction

These definitions include structure definition, operation method definition, and so on.

Database schema definition language is not a programming language. DDL database schema definition language is a part of SQL language (structured query language). SQL language includes four main programming language categories of statements: data definition language (DDL), data manipulation language (DML), data Control language (DCL) and transaction Control language (TCL).

The implementation of query statement rewriting is mainly to rewrite two kinds of statements in SQL language, namely, data definition language DDL and data manipulation language DML.

The schema described by DDL must be compiled by computer software and converted into a format that is convenient for computer storage, query and manipulation. The program that completes this conversion work is called the schema compiler.

The schema compiler processes schema definitions to produce two main types of data: data dictionaries and data types and structure definitions.

The data dictionary and the internal structure information of the database are the basis for creating the database corresponding to the schema, and the corresponding logical structure of each database is created according to this information; the access and query of the database data also determines the way and type of data access according to the schema information, as well as the relationship between the data and the integrity constraints on the data.

The data dictionary is the internal information representation of the schema, and the data dictionary is stored differently for different DBMS.

The definition of data type and structure means that when the application connects to the database, the application needs to understand the data type and structure generated and extracted. It is the definition of the data type and structure of the user workspace provided for various host languages, which makes the logical structure of the user workspace consistent with the database and reduces the process of data conversion. The definition of this data type and structure is usually implemented by a header file.

There are usually two ways to define database schemas: interactively defining schemas and describing text schemas through data description language DDL.

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