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What parts does sql language include?

清浅

May 09, 2019 am 11:36 AM

SQL语言

SQL language includes: 1. "DQL" data query language; 2. "DML" data manipulation language; 3. "TPL" transaction processing language; 4. "DCL" data control language; 5 , "DDL" data definition language; 6. "CCL" pointer control language, etc.

What parts does sql language include?

sql language includes: data query language, data operation language, transaction processing language, data control language, data definition language and pointer control language

What parts does sql language include?

1. Data Query Language (DQL)

Its statements, also called "data retrieval statements", are used to obtain data from tables. Determine how data is presented in the application. The reserved word SELECT is the most commonly used verb in DQL (and all SQL). Other commonly used reserved words in DQL include WHERE, ORDER BY, GROUP BY and HAVING. These DQL reserved words are often used with other types of SQL statements.

2. Data Manipulation Language (DML)

Its statements include INSERT, UPDATE and DELETE. Used to add, modify and delete records in the table respectively. Also known as Action Query Language.

3. Transaction Processing Language (TPL)

Its statements can ensure that all rows of the table affected by the DML statement are updated in a timely manner. TPL statements include BEGIN TRANSACTION, COMMIT and ROLLBACK.

4. Data Control Language (DCL)

Its statements are licensed through GRANT or REVOKE to determine the access of individual users and user groups to database objects. . Some RDBMS can use GRANT or REVOKE to control access to individual columns of a table.

5. Data Definition Language (DDL)

Its statements include the verbs CREATE, DROP, and ALTER. Create a new table or delete a table in the database (CREATE TABLE or DROP TABLE or ALTER TABLE); operate the structure of the table and add indexes to the table.

6. Pointer Control Language (CCL)

Its statements, such as DECLARE CURSOR, FETCH INTO and UPDATE WHERE CURRENT are used to manipulate individual rows of one or more tables ( record) operations.

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