Re: SQL Standard on parentheses

"Jeff Zucker" <jeff_at_vpservices.com> wrote in message news:3C7AA6DE.E24EB680_at_vpservices.com...
> I can't find anything in any of the standards which says whether this is
> a valid statement:
>
> SELECT *
> FROM a
> WHERE (b < c)
> AND (d > e)
>
> The parentheses obviously don't indicate anything about precedence. Is
> a standards complying parser obligated to accept these purely
> "decorative" additions or even uglier things like:
>
> ... WHERE ( (b<c) AND (d>e) ) ORDER BY f
>

The standard seems perfectly clear on this. Here is the relevant SQL-99 grammar
(the SQL-92 grammar is somewhat different, but it still allows all of the above
cases):

<search condition> ::= <boolean value expression>

<boolean value expression> ::=

      <boolean term>
    | <boolean value expression> OR <boolean term>

<boolean term> ::=

      <boolean factor>
    | <boolean term> AND <boolean factor>

<boolean factor> ::=

      [ NOT ] <boolean test>

<boolean test> ::=

      <boolean primary> [ IS [ NOT ] <truth value> ]

<truth value> ::=

      TRUE
    | FALSE
    | UNKNOWN <boolean primary> ::=

      <predicate>
    | <parenthesized boolean value expression>
    | <nonparenthesized value expression primary>

<parenthesized boolean value expression> ::=
      <left paren> <boolean value expression> <right paren>