DDL Full Form is Data Definition Language. DDL is a set of a command language that is used to clarify the structure of the database. The DDL statements can create, modify or remove database objects such as indexes, schemas, tables and also the users. Frequently used DDL statements include; CREATE – to create a new table in the target database; ALTER – to modify existing table like adding new column etc. in database; DROP – to completely delete a table, index or view. These commands are primarily be used by database administrators during various phases of a database project.
DDL is considered to be a part of Structured Query Language (SQL) meant to create tables as per the syntax. Since DDL is a subset of SQL it doesn’t include all the SQL commands. Some commands like SELECT, INSERT are part of DML (Data manipulation Language). It is used as a formal language describing data in the database industry. Data definition language has a predefined Syntax for describing a data.
DDL can also be used to define a name or rename each column and associated data.DDL was first introduced in association with the Codasyl database model. Data type syntax varies from system to system. Some DDL command occurs inside a transaction and thus can be rolled back.A referential integrity relationship is defined by DDL in SQL and is sometimes implemented as primary and foreign key tags in table columns.