With integrity constraints, data validation can be performed as data is being entered into a table. With check constraints, the values are compared to a list of valid entries. And with a lookup table, the valid entries are stored in a small table that is
- One of the most important things…about having your data stored in a database…is being able to trust…that the data has been entered correctly.…The database management system…can protect you in a number of ways…from getting invalidated into…the database in the first place…through a series of rules called "integrity constraints".…Sometimes integrity constraints…are implemented through a new related data table.…For instance, when storing a two letter state abbreviation…you might refer to a separate state lookup table…to ensure that the entered value…appears in the table of valid state abbreviations.…
Lookup tables will include all of the valid choices…for a particular piece of data.…A second approach to the same problem…is to create what's called "a check constraint",…or in Microsoft Access it's known as a validation rule.…Here we can build the constraint…right into the design of the table itself…without needing any additional tables.…The advantage to this approach is, well,…one less table in your database.…The disadvantage is that if the constraint changes…
Adam Wilbert covers the basics of relational database design, regardless of whether you use Access, FileMaker, Open Office, or SQL Server. Learn how to prevent data anomalies, gather requirements to plan your design, and develop a conceptual data model—translating your ideas into components like tables, relationships, queries, and views. Plus, learn about logical design considerations that can help you construct a database that is easy to maintain.
- What is a database management system (DBMS)?
- Moving through the database development cycle
- Preventing duplicate, inconsistent, and conflicting data entries
- Gathering requirements
- Developing relationships
- Identifying key fields
- Following a naming convention
- Developing the actual database
Skill Level Beginner
1. Relational Database Basics
Relational structures3m 46s
2. Preventing Data Anomalies
3. Gathering Requirements
4. Developing the Conceptual Data Model
5. Normalizing Your Data
6. Logical Design Considerations
7. Developing the Physical Database
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