Fix alias-for-target-table-of-UPDATE-or-DELETE patch so that alias can

be any ColId other than 'SET', rather than only IDENT as originally.
Per discussion.

diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 22e20165b96aec1d3e3e71b4c9aff2c55ab62a49..82d36cea023bda50c1d9ba2b135ad6ff6aaa5b03 100644 (file)
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.523 2006/01/22 05:20:33 neilc Exp $
+ *       $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.524 2006/01/22 20:03:16 tgl Exp $
  *
  * HISTORY
  *       AUTHOR                        DATE                    MAJOR EVENT
@@ -429,6 +429,7 @@ static void doNegateFloat(Value *v);
 %token <ival>  ICONST PARAM
 
 /* precedence: lowest to highest */
+%nonassoc      SET                             /* see relation_expr_opt_alias */
 %left          UNION EXCEPT
 %left          INTERSECT
 %left          OR
@@ -5880,11 +5881,27 @@ relation_expr:
                ;
 
 
-relation_expr_opt_alias: relation_expr
+/*
+ * Given "UPDATE foo set set ...", we have to decide without looking any
+ * further ahead whether the first "set" is an alias or the UPDATE's SET
+ * keyword.  Since "set" is allowed as a column name both interpretations
+ * are feasible.  We resolve the shift/reduce conflict by giving the first
+ * relation_expr_opt_alias production a higher precedence than the SET token
+ * has, causing the parser to prefer to reduce, in effect assuming that the
+ * SET is not an alias.
+ */
+relation_expr_opt_alias: relation_expr                                 %prec UMINUS
                                {
                                        $$ = $1;
                                }
-                       | relation_expr opt_as IDENT
+                       | relation_expr ColId
+                               {
+                                       Alias *alias = makeNode(Alias);
+                                       alias->aliasname = $2;
+                                       $1->alias = alias;
+                                       $$ = $1;
+                               }
+                       | relation_expr AS ColId
                                {
                                        Alias *alias = makeNode(Alias);
                                        alias->aliasname = $3;
@@ -6827,7 +6844,7 @@ a_expr:           c_expr                                                                  { $$ = $1; }
                                                $$ = (Node *) makeSimpleA_Expr(AEXPR_IN, "<>", $1, $4);
                                        }
                                }
-                       | a_expr subquery_Op sub_type select_with_parens %prec Op
+                       | a_expr subquery_Op sub_type select_with_parens        %prec Op
                                {
                                        SubLink *n = makeNode(SubLink);
                                        n->subLinkType = $3;
@@ -6836,14 +6853,14 @@ a_expr:         c_expr                                                                  { $$ = $1; }
                                        n->subselect = $4;
                                        $$ = (Node *)n;
                                }
-                       | a_expr subquery_Op sub_type '(' a_expr ')' %prec Op
+                       | a_expr subquery_Op sub_type '(' a_expr ')'            %prec Op
                                {
                                        if ($3 == ANY_SUBLINK)
                                                $$ = (Node *) makeA_Expr(AEXPR_OP_ANY, $2, $1, $5);
                                        else
                                                $$ = (Node *) makeA_Expr(AEXPR_OP_ALL, $2, $1, $5);
                                }
-                       | UNIQUE select_with_parens %prec Op
+                       | UNIQUE select_with_parens
                                {
                                        /* Not sure how to get rid of the parentheses
                                         * but there are lots of shift/reduce errors without them.
@@ -6901,7 +6918,7 @@ b_expr:           c_expr
                                { $$ = (Node *) makeA_Expr(AEXPR_OP, $1, NULL, $2); }
                        | b_expr qual_Op                                        %prec POSTFIXOP
                                { $$ = (Node *) makeA_Expr(AEXPR_OP, $2, $1, NULL); }
-                       | b_expr IS DISTINCT FROM b_expr        %prec IS
+                       | b_expr IS DISTINCT FROM b_expr                %prec IS
                                {
                                        $$ = (Node *) makeSimpleA_Expr(AEXPR_DISTINCT, "=", $1, $5);
                                }
@@ -6910,7 +6927,7 @@ b_expr:           c_expr
                                        $$ = (Node *) makeA_Expr(AEXPR_NOT, NIL,
                                                NULL, (Node *) makeSimpleA_Expr(AEXPR_DISTINCT, "=", $1, $6));
                                }
-                       | b_expr IS OF '(' type_list ')'        %prec IS
+                       | b_expr IS OF '(' type_list ')'                %prec IS
                                {
                                        $$ = (Node *) makeSimpleA_Expr(AEXPR_OF, "=", $1, (Node *) $5);
                                }