week 11 database design. table instance charts create tables
TRANSCRIPT
Common Data Types in Access
• Autonumber• SHORT Text• LONG Text• Number• Currency• Date/Time• Yes/No
Autonumber
• Use for unique sequential numbering• Commonly used for PK (Primary Key)• Increments by 1• Automatically inserted when a record is added.
SHORT Text
• Used for text or combinations of text and numbers, such as addresses, or for numbers that do not require calculations, such as phone numbers, part numbers, or postal codes.
• Stores up to 255 characters.
LONG Text
• Use for lengthy text and numbers, such as notes or descriptions.
• Should be used “sparingly”, because it takes up too much room in database
• Stores up to 65,536 characters (if not more)
Number
• Use for data to be included in mathematical calculations, except calculations involving money (use “Currency” type). • When you are creating a RELATIONSHIP with an
“AUTOnumber” field with the “PARENT” table
Yes/No
• Use for data that can be only 1 of 2 possible values, such as • Yes/No, • True/False, • On/Off.
• Null values are NOT allowed
Rule
• One chart completed for each table
• Click here to open: “TableInstanceChart.xlsx”
Review Relationship Essentials• Need a primary key• EVERY TABLE NEEDS A PRIMARY KEY• Should be 1st field
• Need a foreign key• a Foreign Key is a column in a table used to reference a
Primary Key in another table.• A table does NOT necessarily have to have a Foreign Key• Whenever you see: “MANY”—this will be the Foreign
Key
• Primary key and foreign keys are essential when you create relationships that join together multiple tables in a database
COMPACTING & REPAIRING A DATABASE
• DATABASE TOOLS > COMPACT & REPAIR button• •As you add, edit, & delete objects, a
database changes in size• •To minimize the size of a database & improve
performance should be done on a regular basis• •Rearranges how a fragmented database is
stored on disk
Want More Information
• If you would like more information on how to use MS Access, click here
• Is a QUESTION to the database-asking for a “set of records” from 1 or more Tables/QueriesMS Access responds by displaying the requested datais a stored question, rather than a stored responseresults automatically update,IF table is edited, it allows you to view & operate on “selected subsets” of your data
QUERIES: DEFINITION
Click here to open: “Northwind Database”
Single Table Queries
• Select fields to display• Sort by?• Simple Conditions• When you enter text into the criteria cell your
text should be enclosed in quotes ("") to distinguish it from other expressions and operators that you may need to add.