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Data Manipulation Language (DML) Data Definition Language (DDL) Data Control Language (DCL) 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 are ...
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).
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 ...
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
Similar commands are available in many SQL systems, but usually as external tools, as opposed to being internal to the SQL language. This makes them unavailable to stored procedures. QUEL has an extremely powerful aggregation capability. Aggregates can be nested, and different aggregates can have independent by-lists and/or restriction clauses.
For instance, ALGOL 68S was a subset of ALGOL 68 designed to make it possible to write a single-pass compiler for this sublanguage. SQL (Structured Query Language) statements are classified in various ways, [5] which can be grouped into sublanguages, commonly: a data query language (DQL), a data definition language (DDL), a data control language (DCL), and a data manipulation language (DML).
DCL—Data Control Language; DCS—Distributed Control System; DCMI—Dublin Core Metadata Initiative; DCOM—Distributed Component Object Model; DD—Double Density; DDE—Dynamic Data Exchange; DDL—Data Definition Language; DDoS—Distributed Denial of Service; DDR—Double Data Rate; DEC—Digital Equipment Corporation; DES—Data ...