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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.
Johns (1936 – 2009) pioneered data-driven learning and coined the term. It first appeared in an article, Should you be persuaded: Two examples of data-driven learning (1991). [1] His paper, From Printout to Handout, [2] is reprinted and discussed at length in Volume 2 of Hubbard's Computer-Assisted Language Learning. [3]
1960, IFIP WG 2.1, ISO [8] ALGOL 68: Application Yes No Yes Yes Yes No Concurrent Yes 1968, IFIP WG 2.1, GOST 27974-88, [9] Ateji PX: Parallel application No Yes No No No No pi calculus: No APL: Application, data processing: Yes Yes Yes Yes Yes Yes Array-oriented, tacit: Yes 1989, ISO Assembly language: General Yes No No No No No
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).
Source: [3] A grammar for a simple language should be defined; so that sentences in the language can be interpreted. When a problem occurs very often, it could be considered to represent it as a sentence in a simple language (Domain Specific Languages) so that an interpreter can solve the problem by interpreting the sentence.
Some of the advantages: [2] [3] Domain-specific languages allow solutions to be expressed in the idiom and at the level of abstraction of the problem domain. The idea is that domain experts themselves may understand, validate, modify, and often even develop domain-specific language programs. However, this is seldom the case. [8]
For example, an interpreter might read ADD Books, 5 and interpret it as a request to add five to the Books variable. Interpreters have a wide variety of instructions which are specialized to perform different tasks, but you will commonly find interpreter instructions for basic mathematical operations , branching , and memory management , making ...