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  2. Data query language - Wikipedia

    en.wikipedia.org/wiki/Data_query_language

    DQL statements are used for performing queries on the data within schema objects. The purpose of DQL commands is to get the schema relation based on the query passed to it. Although often considered part of DML, the SQL SELECT statement is strictly speaking an example of DQL. When adding FROM or WHERE data manipulators to the SELECT statement ...

  3. Data manipulation language - Wikipedia

    en.wikipedia.org/wiki/Data_manipulation_language

    A DML is often a sublanguage of a broader database language such as SQL, with the DML comprising some of the operators in the language. [1] Read-only selecting of data is sometimes distinguished as being part of a separate data query language (DQL), but it is closely related and sometimes also considered a component of a DML; some operators may ...

  4. Delete (SQL) - Wikipedia

    en.wikipedia.org/wiki/Delete_(SQL)

    It is a DML (Data Manipulation Language) command, therefore the following commands are used for this command: COMMIT and ROLLBACK; Deletes all or some records from the table, you can limit the records to be deleted by using the WHERE clause; Does not free the space occupied by the data in the table (in the TABLESPACE)

  5. Select (SQL) - Wikipedia

    en.wikipedia.org/wiki/Select_(SQL)

    In most applications, SELECT is the most commonly used data manipulation language (DML) command. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it. The database translates the query into a "query plan" which

  6. Data definition language - Wikipedia

    en.wikipedia.org/wiki/Data_definition_language

    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 ...

  7. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    Queries can be nested so that the results of one query can be used in another query via a relational operator or aggregation function. A nested query is also known as a subquery. While joins and other table operations provide computationally superior (i.e. faster) alternatives in many cases, the use of subqueries introduces a hierarchy in ...

  8. Truncate (SQL) - Wikipedia

    en.wikipedia.org/wiki/Truncate_(SQL)

    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.

  9. Database trigger - Wikipedia

    en.wikipedia.org/wiki/Database_trigger

    Limited support for triggers in the MySQL/MariaDB DBMS was added in the 5.0 version of MySQL, launched in 2005. [4] 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.