2. Database
Collection of related data and tools to use, manage
data
Relational database
Data stored in tables
Each table stores data about one thing
Common values create connections (relationships)
between tables
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3. Fields, Records, and Tables
Fields
Basic unit of data represented by a column in a table
datasheet
Records
Group of related fields or all fields related to a specific
item: person, place, or thing
Each row of a datasheet represent a record
Tables
Group of related records
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4. Planning a Database
What information do you want to obtain?
What data elements (fields) must you include to be able to get
the information?
What types of data will you enter into each field?
Dates, numeric values, amounts of money, text, etc.
What fields of data relate to the same basic items and belong
grouped together?
How do the groups of data relate to each other?
What questions will you need the database to be able to answer?
What is the most efficient way to get data into the database
tables?
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5. Creating Tables
Each table should contain fields that focus on data
specific to one type of item
Such as customers, employees, inventory, etc.
Each table should have a primary key
Fields in the primary key cannot be empty (null)
May be one or more fields
Each generic field# heading is replaced with a
descriptive field name
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6. Table Design Guidelines
Store all necessary data
Store data in smallest parts
Avoid calculations
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7. Using Table Design View
Presents a blank work area on which to enter
fields
Provides tools for setting data
types, descriptions, and properties
Enables you to change the structure and
organization of fields in the table
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8. Entering Field Names
Field names:
Short but descriptive
Can contain alpha-numeric characters
Can contain many symbols
Can contain spaces
Must start with a character or symbol
May use naming convention
Identify table, data type, and field description
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9. Identifying Data Types
Data types identify the kind of data to be added to a
field
Text
Numbers
Dates/Times
Currency
Setting a data type controls values that the field
contains
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10. AutoNumber Fields
Fields that automatically number records as you add
them to a table
Numbers can’t be entered or changed by user
If you delete a record from a table, or cancel a new
row, Access never assigns the number to any new
record
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11. Field Properties
Field Size determines how much data can be stored
Some data type sizes are fixed – date/time, yes/no
Format controls how a value is displayed
Input Mask controls which keyboard entries will be
required and accepted
Validation Rule sets limits on values that a field will
accept
Validation Rule applies regardless of how data is entered
or changed
Set Validation Text to explain how to correct an entry
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12. Operators
Operators are used in validation, calculations and
queries
Comparison Operators:
Relational Operators (=, >, <, <>, >=, <=)
Patterns (Like)
Compare to a list (In)
Logical operators define how to tie tests together
And, Or, Not
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13. Using Wildcards
Used in patterns instead of specific characters
Primary wildcards used:
* Represents any number of characters
? Represents an individual character
Examples:
*Graham* locates all records with graham within the
text
Gra?am locates all records with gra at the beginning of
the field value and am at the end of the field value with
only one letter between
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14. Relational Databases
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
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15. One to Many Relationships
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
16. Many to Many Relationships
Two tables 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
Entries in the join table point to rows in the original
tables
17. Foreign Key
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
18. Referential Integrity
Makes sure 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”
Cannot delete 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
19. Editing Data
Making new entries, changing existing entries, and
deleting rows are all affected by referential integrity
A customer can be added at any time
Must have a customer before a loan can be entered and
associated with a customer
Referential integrity doesn’t require entry into a foreign key
Can delete a loan at any time, but can only delete a
customer if they don’t have any loans (assuming no
cascade delete)
20. Cascading Changes
When referential integrity is enforced can choose to
include Cascade Update and/or Cascade Delete
Cascade update passes changes to the primary key of the
“one” table to the related rows in the “many” table
Cascade delete removes rows from the “many” table
when a primary key (row) is deleted from the “one” table
21. Relationships Window
Where relationships between tables are created and
defined
Related fields must have the same data type
Autonumber is related to number field with long integer
field size
The one table has a 1 next to it; the many has a next
to it
22. Autolookup Queries
Use queries to automatically look up data from related
tables
Must contain the foreign key from the many table
Can add, change or delete data in the source tables
