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Primary Keys

  • Every table contains a primary key field, serving as a distinctive identifier:
    • Each data item in this field is unique.
    • Attempting to input duplicate data items into the primary key field is prevented.
  • Due to the uniqueness of data items within the primary key field, they can effectively identify individual records.

A Database Table Containing Customer Details

Primary Keys | Computer for GCSE/IGCSE - Year 11

  • In the given customer table example, the primary key would likely be the CustomerID since each customer possesses a unique ID.
  • Even if multiple customers share the same name, they can be accurately identified using their respective CustomerID.
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FAQs on Primary Keys - Computer for GCSE/IGCSE - Year 11

1. What is a primary key in the context of database tables?
Ans. A primary key is a unique identifier for a record in a database table. It ensures that each record is distinct and can be easily located within the table.
2. Why is it important to have primary keys in database tables?
Ans. Primary keys are important in database tables as they help in ensuring data integrity, enforcing uniqueness, and establishing relationships between different tables.
3. Can a primary key be duplicated within a database table?
Ans. No, a primary key cannot be duplicated within a database table. Each record must have a unique primary key value to maintain the integrity of the data.
4. How are primary keys different from foreign keys in database tables?
Ans. Primary keys uniquely identify records within a table, while foreign keys establish relationships between tables by referencing the primary key of another table.
5. What are some examples of primary keys commonly used in database tables?
Ans. Examples of primary keys include student IDs, order numbers, employee IDs, and customer account numbers. These are unique identifiers for each record in a table.
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