The most common relationship between tables is one-to-many. In this video, Adam defines what that means and shows how to deduce the relationship type by analyzing the cardinality rules that were previously determined.
- [Instructor] In a relational database, … there are three different kinds of relationships … that can be made between two tables. … The most common, by a large margin, … is a one-to-many relationship. … If you think about your own life … you'll easily find one-to-many relationships all around. … Your one library card has been used … to check out many books. … Your one bank account has had many transactions. … One-to-many relationships are everywhere. … A one-to-many relationship doesn't mean … that there is absolutely multiple related records though. … It simply means that the database is configured … to support the possibility. … The relationship describes the tables not the data. … Consider my library card, number 5005. … In the beginning, I just opened the account … and haven't checked out any books yet. … The account is created in the Library Patron table … but there are no matching records in the Book Loans table. … Bu the relationship between the two tables still … needs to be a one-to-many relationship. …
Author
Adam Wilbert
Released
9/23/2019- The basics of data storage
- Choosing an entity-relationship design tool
- Using primary keys to identify records
- What to consider when naming objects
- Creating a unique constraint
- Establishing table indexes
- Relating tables with foreign keys
- One-to-many and one-to-one relationships
- Normalization
- Writing SELECT queries in SQL
Skill Level Intermediate
Duration
Views
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Introduction
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1. Get to Know Relational Databases
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What the CRUD?3m 48s
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2. Entity Relationship Diagrams
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Choose an ER design tool5m 7s
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Design a table3m 39s
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3. Data Integrity and Validation
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Data constraints1m 44s
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Create a unique constraint5m 46s
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Define a default value3m 58s
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Establish table indexes4m 49s
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Add check constraints5m 31s
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4. Relationships
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Diagram a relationship2m 42s
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One-to-many relationships2m 10s
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One-to-one relationships1m 10s
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Many-to-many relationships2m 21s
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Self joins2m 17s
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Cascade changes2m 17s
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5. Normalization
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When not to normalize2m 29s
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6. Structured Query Language
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Data definition queries6m 22s
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Data manipulation queries4m 52s
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Create a database view2m 44s
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7. Beyond the Relational Model
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Graph databases1m 38s
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Document databases1m 32s
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Conclusion
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Next steps59s
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Video: One-to-many relationships