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Basic Database Concepts
Tutoring > Databases > Basic Database Concepts
A database is a collection of data which is structured such that it can be useful. A database is essentially a fairly sophisticated data structure holding entities of specifically designed types
Entities
An entity in a database is a "thing". It has attributes and there can be many entities. To make it easy, we can look at an entity as a row in a table.
Attributes
Attributes are the types of values relating to each entity. For example, if an entity is an employee, an attribute might be their first name, their phone number or their employee ID number.
Tables
In a database, we can represent the data with tables. As mentioned, the rows are entities and the columns are attributes.
There can be no blank/empty cells! The value can be NULL, but they cannot be empty.
Operations on tables
In order for databases to be useful, we can perform operations on the tables to find or manipulate entries in tables. For example, we might want to search a huge database for some person's name and phone number. We can use queries to refine our search.
We can also add, delete, change and list entries in a database.
Also we may want to add columns (change the shape of the table) or add rows (add entities).
SQL Basics explains the SQL language and goes through some operations.