Introduction
PostgreSQL is an object-relational database management system.
SQL (pronounced “sequel”) stands for Structured Query Language. It is a standard way for working with relational databases. Working with a relational database simply means you will be dealing with tables.
Basic Terminology
- Relation
- The table.
- Relation name
- Name of the table.
- Attributes
- Column headers, used in schemas.
- Tuples
- Rows of data.
- Relational schema
- A relation's name, attribute list and attribute types (optional).
- Database
- The collection of relations or schemas (tables).
- Database schema
- The set of all relation schemas in the database.
Example
See how some of afforementioned terminology in this table is identified.
| Name | Type | Founded | HQ |
|---|---|---|---|
| Walmart | Retail | 1962 | United States |
| Disney | Entertainment | 1923 | United States |
| PayPal | Finance | 1998 | United States |
| Blackberry | Technology | 1984 | Canada |
| Terminology | Example |
|---|---|
| Relation name | Companies |
| Attributes | name, type, founded, hq |
| Tuples | All rows (except attribute row) |
| Relational schema | Companies (name, type, founded, hq) |
| Relational schema with attributes | Companies (name: String, type: string, founded: int, hq: string) |
Note that keys should be underlined in relational schemas.