1. SQL statement consists of reserved words and user-defined words.
  2. Reserved words are a fixed part of SQL and must be spelt exactly as required and cannot be split across lines.
  3. User-defined words are made up by user and represent names of various database objects such as relations, columns, views.
  4. Most components of an SQL statement are case insensitive, except for literal character data.
  5. Each clause should begin on a new line.
  6. Start of a clause should line up with start of other clauses.