Structure of Retrieval Queries

A retrieval query requests data from the database.  At its simplest, a retrieval query merely fetches all data from a single table.  But as you create more complex (and more typical) retrieval queries, you can assemble exactly the data you want in the following ways:

• Including or Excluding Rows
  
• Including or Excluding Columns
  
  
• Combining Tables
  
  
• Collapsing Groups of Rows
  
  
• Using a Table Twice in One Query
  
  
• Using Something Else in Place of a Table
  
  
• Sorting Rows