Numbering Rows

 Unique identification numbers and short character codes allow references to specific rows in a table. They were used extensively in Chapter . For example, the customer table had a customer_id column that held a unique identification number for each customer. The employee and part tables included similar uniquely numbered columns that were important for joins to those tables.

While unique character codes must be supplied by users, unique row numbers can be generated automatically using two methods. This chapter describes how to use these methods.

 

• Object Identification Numbers (OIDs)
• Object Identification Number Limitations
  • Nonsequential Numbering
  • Nonmodifiable
  • Not Backed Up by Default
• Sequences
• Creating Sequences
• Using Sequences to Number Rows
• Serial Column Type
• Manually Numbering Rows
• Summary