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Database
Unit 10 Summary - part 1
What is Database?
Entities
are data in a database, such as employees, customers, objects, events, etc.
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Tables
contain entities, example table 1 is about employees' data, table 2 is about employees' salary, table 3 is about employees' daily attendance.
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Records
are data in rows.
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Fields
are data in columns.
Primary Key
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is a different/unique code for each record. This is very helpful if you have 2 employees/customers/students having the same name, so they are given different codes to distinguish them in the database.
Foreign Key
is a primary key from other tables, used to link tables.
Relational Database
a link between tables so you don't need to duplicate records, you just need to copy the primary key. The computer will look up the details using the primary key.
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