Primary key

As explained in Building Web APIs with ASP.NET Core

A primary key is a property or column whose value uniquely identifies a record in an entity or table.

A primary key is a property or column whose value uniquely identifies each record of a given type. In SQL, it provides the stable identity needed to connect related table records. section 4.1.1

Use primary keys to structure relationships in a table-oriented database:

• Give each record in tables such as Users, Roles, BoardGames, and Comments a unique identity. section 4.1.1
• Add a referencing column where another table needs to point to a record; Comments can use BoardGameID to associate each comment with one board game. section 4.1.1
• Contrast this design with NoSQL, where related information is often embedded in parent documents and key-based relationships are used selectively. section 4.1.1

Figure 4.1 MyBGList database schema diagram for a table-oriented SQL database

Use the SQL schema diagram to trace primary-key identities and the columns that reference related records across tables. section 4.1.1

How Building Web APIs with ASP.NET Core covers it

How deep it goes

Defines uniqueness and demonstrates cross-table references, but stops short of explaining key-generation or constraint implementation.

Examples

Uses Users, Roles, BoardGames, Comments, and the Comments.BoardGameID reference as concrete schema examples.

What you can do after

Evaluate how a relational schema identifies records and represents relationships between tables.

How it connects

Connects primary keys with SQL databases, table relationships, database schemas, NoSQL databases, and document embedding.

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Also explained in

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  ScyllaDB in ActionA primary key is a table key that uniquely identifies rows and determines their key-based ordering.
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  Grokking Relational Database DesignA primary key constraint is an SQL constraint that requires primary-key values to be unique and non-NULL within a table.
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  Learn SQL in a Month of LunchesA primary key constraint is a database rule requiring a table's primary-key values to uniquely identify rows and not be null.
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  DuckDB in ActionA primary key is a column or combination of columns whose values uniquely identify every row in a table.
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  Amazon Web Services in Action, Third Edition: An in-depth guide to AWSA DynamoDB primary key is the attribute or combination of attributes that uniquely identifies an item in a table.
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  Functional Design and Architecture: Examples in HaskellA primary key is a field or combination of fields that uniquely identifies a record in a database.
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  Build Python Web Apps with StreamlitA primary key is a column or set of columns whose combined values uniquely identify each row in a data table.
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  Kafka Streams in Action, Second EditionA primary key is a field or set of fields that uniquely identifies a row in a database table.
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  Java Persistence with Spring Data and Hibernate epubA primary key is a database column or set of columns whose values uniquely identify a row.
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  Effective Data AnalysisA primary key is a field or combination of fields that uniquely identifies a record in a dataset or table.
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  The Well-Grounded Python Developer: How the pros use Python and FlaskA primary key is a column or set of columns that uniquely identifies each record in a relational database table.
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  100 SQL Server Mistakes and How to Avoid ThemA primary key is a column or set of columns that uniquely identifies each row in a table.
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  Just Use Postgres!A primary key is a column or set of columns that uniquely identifies each row in a table and cannot contain null values.
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  AI-Powered Developer: Build software with ChatGPT and CopilotA primary key is a column or set of columns that uniquely identifies each row in a relational table.
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  Spring in Action, Sixth EditionA primary key is a Cassandra key definition that identifies rows and can combine partitioning and clustering components.
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  .NET in Action, Second EditionA primary key is a column or set of columns whose values uniquely identify rows in a database table.
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Compare how 21 books explain primary key →

Related concepts

• database tablepart of · A database table is a relational database structure that organizes records into rows and defined columns.
• composite keyincludes · A composite key is a key formed from multiple attributes or values whose combination identifies or uniquely distinguishes a record or item.
• attributeuses · An attribute is a named property, value, or piece of information associated with an entity, object, or program element.
• foreign keyused by · A foreign key is a column or set of columns in a relational table whose values reference a candidate key in the same or another table, establishing a relationship and supporting referential integrity.
• partitioning keyhas part · A partitioning key is a value or attribute used to determine which partition stores or receives a record or data item.

This explainer was generated by Manning's knowledge graph from the text of Building Web APIs with ASP.NET Core. The section links point to the parts of the book it draws on.