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Data Definition Language (DDL)

Data Definition Language (DDL) is a type of SQL command that is used to define, modify, and manage the structure of database objects such as tables, indexes, schemas, and views.

  • It primarily focuses on the creation, alteration, and deletion of database schema and its components.

Key Operations of DDL:

  • CREATE: Used to create new database or objects in a database.
  • ALTER: Used to modify the structure of a database, such as adding or dropping columns in a table.
  • DROP: Deletes a database object from the database permanently.
  • TRUNCATE: Deletes data from table.
  • RENAME: Used to rename a table or a column.
  • COMMENT: Used to comment on the data dictionary.

In Oracle, data types are used to define the type of data that can be stored in a column. Oracle provides a wide range of data types, allowing users to store various kinds of data such as numbers, strings, dates, and more.

Here’s a breakdown of the most commonly used Oracle data types:

  • Numeric data types: NUMBER, INTEGER, FLOAT, BINARY_FLOAT, BINARY_DOUBLE.
  • Character data types: CHAR, VARCHAR2, CLOB.
  • Date and Time data types: DATE, TIMESTAMP, INTERVAL.
  • Large object data types: BFILE, BLOB, CLOB, NCLOB.
  • Rowid Data types: ROWID, UNROWID(SIZE)

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