Data Validation

Data Validation

1. Type Check - These are used to Validate fields. Field data types are assigned to fields during the creation of the database table and data types such as Numeric, Boolean, Image restrict and Date/Time can only be entered. If a user tries a different data type it won't allow it.

2. Range Check - These are used to limit the range of data a user can enter. The 'day' part of a date must be in the range 1 to 31. An exam grade should be in the range 'A'...'G' or 'U'.

3. Presence Check - To check that something has been entered in the specific field.

4. Length Check - So that the user can only enter a specific amount of letters or numbers in one field.

5. Lookup - A lookup checks the value entered and compares it against a list of values in a separate table.

6. Input Mask - Data must be entered in a specific way. E.G: Including a space in a phone number.

7. What is a Database? A database is a persistent, store of related data.

8. Flat-file database - A database of only one table.

9. Relational Database - A database with multiple tables linked by common fields.