Databases-Tools and techniques-Tables

Databases-Tools and techniques-Tables

1. Table characteristics

   • Columns=Fields
   • Rows=Records
   • Field types
     • Alphabetic
       • Text
       • Memo
     • Numeric
       • Numbers
       • Time
       • Currency
     • Boolean
       • Yes/No
       • True/False
     • Web
       • Hyperlinks
     • Lookup wizards
   • Field size
     • Byte
     • Integer
     • Long integer
     • Single
     • Double
     • Decimal
   • Field formats
     • Fixed
     • Decimal places
   • Default values

2. Validation

   • To check for errors
   • Applies to a range
   • Correct format
   • Correct field size
   • Correct data type
   • Examples
     • Check digits
       • The last one or two digits in a code are used to check the other digits are correct
     • Format check
       • Checks the data is in the right format
     • Length check
       • Checks the data isn't too short or too long
     • Lookup table
       • Looks up acceptable values in a table
     • Presence check
       • Checks that data has been entered into a field
     • Range check
       • Checks that a value falls within the specified range
     • Spell check
       • Looks up words in a dictionary

3. Records

   • Edit
   • Add
     • Manually
     • External source
       • Spreadsheets
   • Delete

4. Indexing

   • Primary key
   • Foreign key

5. Realationships

   • One to one
   • Mnay to many
   • One to many