[antlr-interest] Re: SQL grammar, keywords that can be identifiers

[olejohnaske]

--- In antlr-interest at yahoogroups.com, Ruslan Zasukhin 
<sunshine at p...> wrote:
> Hi All,
> 
> It seems in the past we have discuss this, but I want ask once 
again.
> 
> We have SQL grammar.
> 
> We have for example the next rule
> 
> join_type
>     :    ("left" | "right" | "full" ) ( "outer"! )?
> 
> 
> But SQL grammar still must accept the next query
> 
>     WHERE left(fld,5) = "Peter"
>           ^^^^^  
> 
> 
> As you see problem is that 'left' is keyword.
> ANTLR mark it as token in Lexer.
> 
> So our function left() simple return error.
> 
> --------------
> Another example of problem. SQL by standard allow to use field and 
table
> names as key words.
> 
>     SELECT *
>     FROM references
>     
> Here "references" is name of table.
> But SQL also have key word 'references'.
> So we get conflict.
> 

Are you sure this is a real problem?

At least according to the SQL92 standard, <reserved words> are not 
allowed as identifiers: My copy of ISO/IEC9075:1992 (SQL92), chapter 
5.2, Part 11) in the 'Syntax rule' states:

11)
The <identifier body> of a <regular identifier> .... shall not be 
equal according to the comparison rules in Subclause 8.2 ... to any 
<reserved words> ....

(Removed some lengthy sql92 phrases where '....' is inserted)

Both Table name and column names are defined as <identifiers> which 
has an <identifier body>. According to this, your examples above are 
not correct SQL92 syntax. (However, it may be allowed by some 
implementation which extends the standard... )

Note: Identifier can be a <non-reserved words>. I handle this in my 
SQL92 parser by:

nonReservedWords :
  CATALOG_NAME | CHARACTER_SET_CATALOG | .... lots more...  ;


identifier :
  IDENT
 | DELIMITED_IDENT
 | nonReservedWord
 ;

Ole John Aske





 
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