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53 lines
2.0 KiB
Markdown
53 lines
2.0 KiB
Markdown
# Data Integrity and ER Diagrams
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## Agenda
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* Data Integrity
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* ER Diagrams
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* Functional Dependencies
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* Normalization
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## Key Terms
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### Schema
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> refers to the organization of data as a blueprint of how the database is constructed
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> In a relational database, the schema defines the tables, fields, relationships, views, indexes, packages, procedures, functions, queues, triggers, types, sequences, materialized views, synonyms, database links, directories, XML schemas, and other elements
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### Data Integrity
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### Entity Integrity
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### Referential integrity
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### Domain integrity
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### User-defined integrity
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### ER Diagrams
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## Schema
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A schema is a blueprint of a database. It is created before you actually construct the database so that the schema design can be reviewed. Schema diagrams are also a great way to document the database structure in one place.
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Remember our student's database from the [previous lesson](01-database-fundamentals.md)? We had the three following tables
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* `students` (id, name, age, address, phone, email, batch ID)
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* `mentors` (id, name, age, address, phone, email)
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* `batches` (id, name, mentor, start date, type, mentor ID)
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So each table has `ID` as primary key. The `students` table has a `batch ID` field that references the `batches` table and the `batches` table has a `mentor ID` field that references the `mentors` table. These are examples of foreign keys. These are some the items that are present in a schema. A schema will also contain indexes, constraints, and other items that are present in a table.
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Following is a schema diagram for the above database. Note that the primary key is not highlighted here, which ideally should be.
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> **Note**
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>
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> Try it yourself. \
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> Go to [this](https://diagramplus.com/) website and import [this](../media/schema.diagram) diagram. \
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> Try adding a new column or even a new table.
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---
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## Data Integrity
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---
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## ER Diagrams
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---
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## References
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## Reading List
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