Term
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Definition
| One or more attributes that determine other attributes |
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Term
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Definition
| Key consisting of two or more attributes |
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Term
| Principle of determination |
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Definition
| If you know the value of attribute A you can determine the value of attribute B |
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Term
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Definition
| Attribute B is functionally dependent on A |
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Definition
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Term
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Definition
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Term
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Definition
| Any column or combination of columns that uniquely identifies |
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Term
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Definition
The most effective superkey that you can obtain.
Least amount of columns
Strive for one |
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Term
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Definition
| The candidate key that you decide to be the primary key |
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Term
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Definition
Helps you obtain certain data a little bit easier
For your convenience
Usually results in multiple records in the output
Then you pick through the output |
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Term
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Definition
Help you link tables
A common field between two tables
Must contain values in the primary key column of the other table |
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Term
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Definition
Very dangerous
Effect calculations and make inadequate results |
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Term
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Definition
| Define requirements for the primary and foreign key columns |
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Term
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Definition
Primary key column
Must contain unique values
Can't contain null values |
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Term
| Referential Integrity Rules |
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Definition
Foreign Key column
Must contain values that appear in the primary key column of the related table
May contain duplicate or null values |
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Term
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Definition
Enables tables to be linked together
Foreign key column |
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Term
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Definition
Relational operators
Theoretical way of manipulating table contents |
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Term
| Types of relational algebra operators |
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Definition
Select
Project
Join
Intersect
Union
Difference
Product
Divide |
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Term
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Definition
| Combines all rows from two tables excluding duplicate rows |
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Term
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Definition
| Only shows the rows that appear in both tables |
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Term
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Definition
| Only shows rows in table 1 that are not found in table 2 |
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Term
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Definition
| Shows all possible combinations of rows from two tables |
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Term
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Definition
| Selects data based on a query |
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Term
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Definition
Shows all values for selected attributes
Only used when you create joints |
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Term
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Definition
| How you retrieve data from two or more tables |
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Term
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Definition
| Links tables by selecting rows with common values in common attributes |
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Term
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Definition
List rows from one or more tables even when there are no matching values in the other table.
Missing values in the second table are set to null |
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Term
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Definition
Bridge Entity
Breaks up M:N relationship |
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Term
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Definition
Holds metadata
Contains all the attributes names and characteristics for each table in the system |
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Term
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Definition
Contains metadata
Detailed data dictionary that includes all objects within the database |
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Term
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Definition
Speeds up the retrieval process
Looks like a table
Each record is listed and given a location |
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Term
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Definition
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Term
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Definition
| Index where index key can only have one row associated with it |
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