Syntax diagrams in this book will utilize what is known as Backus-Naur Form syntax notation convention. Backus-Naur Form has become the de facto standard for most computer texts. Oracle SQL is used to describe the notation.

• Angle brackets: < . . . >. Angle brackets are used to represent names of categories (substitution variable representation). In this example

  will be replaced with a table name in a schema as shown.

  SELECT * FROM ;

  Becomes:

  SELECT * FROM ARTIST;

  Note	Angle brackets are generally not used in this book unless stated as such at the beginning of a chapter.

• OR: . A pipe or character represents an OR conjunction meaning either can be selected. The asterisk (*) and curly braces ({}) are explained further on. In this case all or some columns can be retrieved, some meaning one or more.

  SELECT { *  { ,   } } FROM ;<a name="1176"></a><a name="beginpage.5FE52202-8220-4105-99AE-F280487E4D2B"></a>

• Optional: [ . . . ]. In a SELECT statement a WHERE clause is syntactically optional.

  SELECT * FROM  [ WHERE  =   ];

• At least one of: { . . . . . . . . . }. In this example the SELECT statement retrieval list must include an asterisk (*), retrieving all columns in a table, or a list of one or more columns.

  SELECT { *  { ,   } } FROM ;

  Note	This is a not precise interpretation of Backus-Naur Form where curly...