This document discusses database design concepts including primary keys, foreign keys, relationships between tables, normalization, and different types of queries. It covers one-to-one, one-to-many, and many-to-many relationships and how to implement them. It also discusses referential integrity, data validation, indexes, anomalies that can occur without normalization, and different types of joins and queries.

1. CIS245

2.  Primary key
 Composite key/multiple-field primary key
 Foreign key
 One-to-one relationship
 One-to-many relationship
 Many-to-many relationship
 Referential Integrity

3.  Have more than one table where tables are
related to each other
 One to one
 One to many
 Many to many
A combination of fields may be used for the
table‟s primary key

4.  Each table contains data about a specific
subject (customers, loans)
 Each table on the „one‟ side has a primary
key
 Primary key of the “one” table is a foreign
key in the many table

5.  Twotables are related, but can have many
records in each table in common
 One student can attend many courses; one
course can be attended by many students
 Implement a many to many relationship by
creating a pair of one to many relationships
with a third table
 Third table is often referred to as a “join” or
“junction” table

6. A foreign key points to a record in another
table
 Foreign key “looks like” the related primary
key
 Same number of fields
 Data types for each field must match
 Field names don‟t matter

7.  Makessure that the records in related tables
are consistent
 Must have a customer in the customer table for
an order assigned to that customer
 Avoids “orphans”
 Cannotdelete a record or change the
primary key in the one table when associated
records are in the many table, unless have
cascade delete and cascade update enabled

8.  Data constraints: What is “good” data?
 Valid type of data
 Valid values for the data
 Many can be enforced through the design of the
Access tables and relationships

9.  Validation rule: Condition that the
corresponding field must satisfy
 Validation text: Displayed if the condition of
validation rule is not satisfied
 Table Properties validation rule: Required
when a constraint requires a comparison of
the contents of two or more fields in the
same table

10.  Maintains a sorted list of the current values
of a field or fields
 Items in the list point to the records that
have the identified value
 Created automatically for primary keys

11.  Normalization is a process
 Goals:
 Reduce space required to store data by
eliminating duplicate data in database
 Reduce inconsistent data in database by storing
data only once
 Reduce chance anomalies

12.  Deletion anomaly
 User deletes data from database
 Unintentionally deletes only occurrence of data
in database
 Update anomaly
 Due to redundant data in database
 User fails to update some records or updates
records erroneously
 Insertion anomaly
 User cannot add data to database unless
preceded by entry of other data

13.  Dependency: Column value depends on value
in a different column
 Functional dependency: values explicitly one to
one
 Partial dependency: Column value dependent on
only part of primary/candidate key

14.  Determinant: Field or collection of fields
whose value determines value in another
field
 Inverse of dependency
 Department is a determinant

15.  Retrieve data from other tables or queries
 Field names appear in the Field row of the
grid
 Criteria row of grid
 Limits the displayed rows to those that meet a
specified condition
 Contains any statement that evaluates to True or
False

16.  Inner join
 Default join type
 Includes rows only when the fields being
compared contain matching values
 Outer join
 Includes all rows from one table and data from
second table where there is a match

17.  Use when selecting records from one table,
but need to limit the records returned by a
value in another table
 Use the „In‟ comparison
 Sub-query can return only a single field
 Sub-query must run before the main query
 Use parentheses to control order of execution

18.  Select queries that aggregate values
 The Group By item in the Total list box tells
Access to aggregate the other fields per each
unique value within the Group By field
 A field that‟s part of the aggregate uses
Having instead of Where

19.  Delete queries: Remove rows from a table
 Make-table queries: Query results are stored
in a new table
 Append queries: Query results of the are
appended (added) to an existing Access table
 Update queries: Change field values in
existing rows in a table

20.  Parameter queries use placeholder to
substitute for the constant values placed in
the query grid
 Allow changes to criteria “on the fly” when
the query is run