SQL objects

 

SQL objects are schemas, journals, catalogs, tables, aliases, views, indexes, constraints, triggers, sequences, stored procedures, user-defined functions, user-defined types, and SQL packages. SQL creates and maintains these objects as system objects.

• Schemas
  A schema provides a logical grouping of SQL objects. A schema consists of a library, a journal, a journal receiver, a catalog, and, optionally, a data dictionary.

• Journals and journal receivers
  A journal and a journal receiver are used to record changes to tables and views in the database.

• Catalogs
  An SQL catalog is a collection of tables and views that describe tables, views, indexes, packages, procedures, functions, files, sequences, triggers, and constraints.

• Tables, rows, and columns
  A table is a two-dimensional arrangement of data that consists of rows and columns.

• Aliases
  An alias is an alternate name for a table or view.

• Views
  A view appears like a table to an application program. However, a view contains no data and only logically represents one or more tables over which it is created.

• Indexes
  An SQL index is a subset of the data in the columns of a table that are logically arranged in either ascending or descending order.

• Constraints
  A constraint is a rule enforced by the database manager to limit the values that can be inserted, deleted, or updated in a table.

• Triggers
  A trigger is a set of actions that runs automatically whenever a specified event occurs to a specified table or view.

• Stored procedures
  A stored procedure is a program that can be called with the SQL CALL statement.

• Sequences
  A sequence is a data area object that provides a quick and easy way of generating unique numbers.

• User-defined functions
  A user-defined function is a program that can be called like any built-in functions.

• User-defined types
  A user-defined type is a distinct data type that you can define independently of the data types that are provided by the database management system.

• SQL packages
  An SQL package is an object that contains the control structure produced when the SQL statements in an application program are bound to a remote relational database management system (DBMS).

 

Parent topic:

Introduction to DB2 UDB for iSeries Structured Query Language