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In the context of SQL, data definition or data description language (DDL) is a syntax for creating and modifying database objects such as tables, indices, and users. DDL statements are similar to a computer programming language for defining data structures, especially database schemas. Common examples of DDL statements include CREATE, ALTER ...
These sub-languages are mainly categorized into four categories: a data query language (DQL), a data definition language (DDL), a data control language (DCL), and a data manipulation language (DML). Sometimes a transaction control language (TCL) [1] is argued to be part of the sub-language set as well.
In SQL, the data manipulation language comprises the SQL-data change statements, [3] which modify stored data but not the schema or database objects. Manipulation of persistent database objects, e.g., tables or stored procedures, via the SQL schema statements, [3] rather than the data stored within them, is considered to be part of a separate data definition language (DDL).
Data Manipulation Language (DML) Data Definition Language (DDL) Data Control Language (DCL [2]) Transaction Control Language (TCL) DCL commands are used for access control and permission management for users in the database. With them we can easily allow or deny some actions for users on the tables or records (row level security). DCL commands ...
The Data Definition Language (DDL) manages table and index structure. The most basic items of DDL are the CREATE, ALTER, RENAME, DROP and TRUNCATE statements: CREATE creates an object (a table, for example) in the database, e.g.:
Data definition language (DDL) – defines data types such as creating, altering, or dropping tables and the relationships among them; Data manipulation language (DML) – performs tasks such as inserting, updating, or deleting data occurrences; Data query language (DQL) – allows searching for information and computing derived information.
As of version 8.0, they allow for DDL (Data Definition Language) triggers and for DML (Data Manipulation Language) triggers. They also allow either type of DDL trigger (AFTER or BEFORE) to be used to define triggers. They are created by using the clause CREATE TRIGGER and deleted by using the clause DROP TRIGGER.
In SQL, the TRUNCATE TABLE statement is a Data Definition Language (DDL) operation that deletes all rows of a table without causing a triggered action. [1] The result of this operation quickly removes all data from a table, typically bypassing a number of integrity enforcing mechanisms.