Some data needs to be unique, even if it's not the table's primary key. In this video, see how to ensure that each value in an attribute column is distinct from all others by attaching a unique constraint to the table.
- [Instructor] In our database diagram … that we started in the previous chapter, … we've already identified the primary keys … for each of these tables: … the Part Number field in the Products table … and the Supplier ID field in the Suppliers table. … Now, I've saved this text that makes up these tables … into the exercise files for the course for your reference. … Now let's suppose we also need to ensure … that the Product Name in the Products table … also has a unique constraint applied to it. … You can make a note of that requirement … in this diagramming application … by simply placing the word "unique" after the data type. … That'll update the diagram on the right … and it displays this little key icon here … on this particular column. … These icons are specific to this diagramming tool, … so you're not going to see them in your RDBMS … when you're actually creating the database … that you're designing here. … But it's just this app's way of noting … the unique constraint on this column. …
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: Create a unique constraint