Database Basics

Something everyone wants to have quick access to ....

1. Catalog: A relational database contains a catalog that describes the various elements in the system. The catalog divides the database into sub-databases known as schemas. Within each schema are database objects -- tables, views and privileges.
The catalog itself is a set of tables with its own schema name - definition_schema. Tables in the catalog cannot be modified directly. They are modified indirectly with SQL-schema statements.
2. Schema: It is a collection of named objects used to provide a logical classification of database objects. It may contain objects such as tables,
views, aliases, indexes, triggers, and structured types.
3. Table: It is a logical structure maintained by database manager which is made up of columns and rows.
4. View: It is a parsed SQL statement which fetches record at the time of execution. It may be thought of as a virtual table that doesn't really exist in its own right but is instead derived from one or more underlying base tables.
5. Alias: The alias names are local synonyms given to certain database object.
6. Index: It is a type of data structure that allows for (potentially) faster access by providing the database with quick jump points on where to find the full reference (or to find the database row).
7. Function: It is a subprogram written to perform certain computations and return a single value.
8. Stored Procedure: It is collection of SQL statments compiled as a program which reside in the database.
9. Trigger: It is procedural code that is automatically executed in response to certain events on a particular table or view in a database.
10. Synonym: It is an object in Oracle that basically allows you to create a pointer to an object that exists somewhere else.
11. Sequence: It is an object in Oracle that is used to generate a number sequence.
12. JOIN: Return rows when there is at least one match in both tables.
13. LEFT JOIN: Return all rows from the left table, even if there are no matches in the right table.
14. RIGHT JOIN: Return all rows from the right table, even if there are no matches in the left table.
15. FULL JOIN: Return rows when there is a match in one of the tables.
16. SELF JOIN: Querying for the result set of join with the same table.