What are the four parts of the function of sql?
#What are the four parts of the function of sql?
SQL language functions are mainly divided into four parts:
(1) Data definition. (DDL) is used to define the creation and undoing operations of SQL schemas, basic tables, views, and indexes.
(2) Data manipulation. (DML) data manipulation is divided into two categories: data query and data update. Data update is divided into three operations: insertion, deletion, and modification.
(3) Data control. Including authorization of basic tables and views, description of integrity rules, transaction control, etc.
(4) Embedded SQL usage regulations. Rules involving embedding SQL statements in host language programs.
Extended information:
DDL is one of the four major functions of the SQL language. Used to define the three-level structure of the database, including external schema, conceptual schema, internal schema and their mutual images, defining data integrity, security control and other constraints. DDL does not require commit.
Recommended tutorial: "sql video tutorial"
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