The second patch adds aliases for "ISNULL" to "IS NULL" and likewise for

"NOTNULL" to "IS NOT NULL".  I have not removed the postgres specific
ISNULL and NOTNULL.  I noticed this on the TODO list, and figured it would
be easy to remove.

The full semantics are:
        [ expression IS NULL ]
        [ expression IS NOT NULL ]

Submitted by: Jason Wright <jason@oozoo.vnet.net>

Author: scrappy

src/backend/parser/gram.y

@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 1.2.2.1 1996/08/24 20:54:06 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 1.2.2.2 1996/10/11 03:28:08 scrappy Exp $
  *
  * HISTORY
  *    AUTHOR		DATE		MAJOR EVENT
@@ -173,7 +173,7 @@ static Node *makeA_Expr(int op, char *opname, Node *lexpr, Node *rexpr);
 	CURSOR, DATABASE, DECLARE, DELETE, DELIMITERS, DESC, DISTINCT, DO,
 	DROP, END_TRANS,
 	EXTEND, FETCH, FOR, FORWARD, FROM, FUNCTION, GRANT, GROUP, 
-	HAVING, HEAVY, IN, INDEX, INHERITS, INSERT, INSTEAD, INTO, 
+	HAVING, HEAVY, IN, INDEX, INHERITS, INSERT, INSTEAD, INTO, IS,
 	ISNULL, LANGUAGE, LIGHT, LISTEN, LOAD, MERGE, MOVE, NEW, 
 	NONE, NOT, NOTHING, NOTIFY, NOTNULL, 
         OIDS, ON, OPERATOR, OPTION, OR, ORDER, 
@@ -201,6 +201,7 @@ static Node *makeA_Expr(int op, char *opname, Node *lexpr, Node *rexpr);
 %nonassoc Op
 %nonassoc NOTNULL
 %nonassoc ISNULL
+%nonassoc IS
 %left  	'+' '-'
 %left  	'*' '/'
 %left	'|'		/* this is the relation union op, not logical or */
@@ -1810,8 +1811,12 @@ a_expr:  attr opt_indirection
 		}
 	| a_expr ISNULL
 		{   $$ = makeA_Expr(ISNULL, NULL, $1, NULL); }
+	| a_expr IS PNULL
+		{   $$ = makeA_Expr(ISNULL, NULL, $1, NULL); }
 	| a_expr NOTNULL
 		{   $$ = makeA_Expr(NOTNULL, NULL, $1, NULL); }
+	| a_expr IS NOT PNULL
+		{   $$ = makeA_Expr(NOTNULL, NULL, $1, NULL); }
 	| a_expr AND a_expr
 		{   $$ = makeA_Expr(AND, NULL, $1, $3); }
 	| a_expr OR a_expr

src/backend/parser/keywords.c

@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/parser/keywords.c,v 1.1.1.1.2.1 1996/08/24 20:54:11 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/parser/keywords.c,v 1.1.1.1.2.2 1996/10/11 03:28:14 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -87,6 +87,7 @@ static ScanKeyword ScanKeywords[] = {
 	{ "insert",		INSERT		},
 	{ "instead",		INSTEAD		},
 	{ "into",		INTO		},
+	{ "is",			IS		},
 	{ "isnull",             ISNULL          },
 	{ "language",		LANGUAGE	},
 	{ "light",		LIGHT		},