Document Conventions

The syntax uses building blocks that are called productions. Productions are denoted by the symbol ::= . To the left of the symbol is a production name; to the right of the symbol, or on the next line, is a list of production constructs. If a production has more than one possible construct, the alternatives are separated by a vertical bar |. Read productions top-down. For example, the delete statement contains literal keywords and two subproductions, a table specification, and then a WHERE clause.

Traversing down a syntax tree leads to leaf or terminal definitions. The definitions consist of either keywords, identifiers (names of tables, columns, and so on), or symbols (punctuation, operators, and so on). Keywords and identifiers are shown with capitalized text. In contrast, symbols are shown with single quotation marks and are bold.

Optional syntax is delimited by square brackets ([ ]). Optional lists (syntax elements that are repeated) are denoted by square brackets, followed by an asterisk (*). The * signifies zero or more occurrences of the bracketed syntax.

Selection lists, which enable you to choose from a list of alternative syntax elements, are denoted by braces ({ }). The alternative elements are separated by a vertical bar (|). The selection list itself is not optional; you must choose at least one element. When you specify one or more elements, the list is terminated with a closing brace and a plus sign (}+). The + indicates one or more occurrences of the delimited syntax.