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AR Adv DB Unit 2
Advanced Database Unit 2
| Question | Answer |
|---|---|
| Primary key | a unique value in a record |
| One–to–one relationship | a relationship between two tables in which each record in the first table matches at most one record in the second table, and each record in the second table matches at most one record in the first table |
| Data redundancy | a condition that occurs when you store the same data in more than one place; it wastes storage space and can cause inconsistencies |
| Common field | a field that appears in more than one table, allowing you to connect or join the records |
| Input mask | a field property you add with a predefined format for entering and displaying data. Useful for phone numbers, zip codes, social security numbers and the like, so that when you are keying in the data you do not have to key in the (), -, etc. |
| Cascade delete/update | a referential integrity rule that when a record in the primary table is deleted or changed, the records in the related tables are also deleted or changed |
| Join | to relate tables through a common field |
| Default value | a field property you insert for values that are the same for most of your records. For example, most of your students are from Arkansas, you can set your State field properties to AR |
| Many–to–many relationship | a relationship between two tables in which each record in the first table matches many in the second table and each record in the second table matches many records in the first table. |
| Lookup field | this can be set so that the values in the field can either be brought in from another table or they can be created by the user. this is useful, so that you did not have to key these info in, but can choose from a drop down list. |
| One–to–many relationship | a relationship between two tables in which each record in the first table matches zero, one or many in the second table, and each record in the second table matches at most one record in the first table |
| Field properties | define the field’s characteristics and behavior, such as data type, field size, etc. |
| Referential integrity | is a set of rules enforced to maintain consistency between related tables when you update data in a database |
Created by:
Jame Pearce
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