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Database keys
Database keys are essential for organizing and managing data effectively. In this post, we'll explore ten key concepts that every IT professional should know.
1. ๐ ๐ฃ๐ฟ๐ถ๐บ๐ฎ๐ฟ๐ ๐๐ฒ๐
- A unique identifier for each record in a table.
- Cannot be null.
- Ensures that each row is unique.
2. ๐ ๐๐ผ๐ฟ๐ฒ๐ถ๐ด๐ป ๐๐ฒ๐
- A field in one table that refers to the Primary Key of another table.
- Establishes relationships between tables.
3. ๐งฉ ๐๐ผ๐บ๐ฝ๐ผ๐๐ถ๐๐ฒ ๐๐ฒ๐
- A combination of two or more columns that uniquely identifies each record.
- Useful when a single column can't uniquely identify a record.
4. ๐ช ๐ฆ๐๐ฝ๐ฒ๐ฟ ๐๐ฒ๐
- One or more columns that can uniquely identify a record.
- A Primary Key is a type of Super Key.
5. ๐
๐๐ฎ๐ป๐ฑ๐ถ๐ฑ๐ฎ๐๐ฒ ๐๐ฒ๐
- A column or set of columns that could be the Primary Key.
- Must be unique.
6. ๐ ๐จ๐ป๐ถ๐พ๐๐ฒ ๐๐ฒ๐
- Ensures uniqueness for a column or column combination.
- Similar to Primary Key but allows one null value.
7. ๐ค ๐๐น๐๐ฒ๐ฟ๐ป๐ฎ๐๐ฒ ๐๐ฒ๐
- A Candidate Key that isn't the Primary Key.
- Another option for a unique identifier.
8. ๐ ๐ก๐ฎ๐๐๐ฟ๐ฎ๐น ๐๐ฒ๐
- A key that's a natural part of the data, like an email address.
9. ๐ญ ๐ฆ๐๐ฟ๐ฟ๐ผ๐ด๐ฎ๐๐ฒ ๐๐ฒ๐
- An artificial key created when no natural unique identifier exists.
10. ๐ ๐ฆ๐ฒ๐ฐ๐ผ๐ป๐ฑ๐ฎ๐ฟ๐ ๐๐ฒ๐
- Used for data retrieval, not identification.
- Helps create non-clustered indexes.
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