Add help information about REFERENCES of column_constraint.

doc/src/sgml/ref/alter_table.sgmlin

@@ -76,7 +76,9 @@ where column_constraint can be:
       CHECK ( expression ) |
       DEFAULT default_expr |
       UNIQUE index_parameters |
-      PRIMARY KEY index_parameters }
+      PRIMARY KEY index_parameters |
+      REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
+        [ ON DELETE action ] [ ON UPDATE action ] }
     [ DEFERRABLE | NOT DEFERRABLE | INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
 where compress_mode can be:
 { DELTA | PREFIX | DICTIONARY | NUMSTR | NOCOMPRESS }

doc/src/sgml/ref/create_table.sgmlin

@@ -31,7 +31,9 @@ where column_constraint can be:
   CHECK ( expression ) |
   DEFAULT default_expr |
   UNIQUE index_parameters |
-  PRIMARY KEY index_parameters }
+  PRIMARY KEY index_parameters |
+  REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
+    [ ON DELETE action ] [ ON UPDATE action ] }
 [ DEFERRABLE | NOT DEFERRABLE | INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
 where table_constraint can be:
 [ CONSTRAINT constraint_name ]

doc/src/sgml/ref/create_table_partition.sgmlin

@@ -35,7 +35,9 @@ where column_constraint can be:
   CHECK ( expression ) |
   DEFAULT default_expr |
   UNIQUE index_parameters |
-  PRIMARY KEY index_parameters }
+  PRIMARY KEY index_parameters |
+  REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
+    [ ON DELETE action ] [ ON UPDATE action ] }
 [ DEFERRABLE | NOT DEFERRABLE | INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
 where table_constraint can be:
 [ CONSTRAINT constraint_name ]

src/test/regress/expected/alter_table_000.out

@@ -72,7 +72,9 @@ where column_constraint can be:
       CHECK ( expression ) |
       DEFAULT default_expr |
       UNIQUE index_parameters |
-      PRIMARY KEY index_parameters }
+      PRIMARY KEY index_parameters |
+      REFERENCES reftable [ ( refcolumn ) ] [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ]
+        [ ON DELETE action ] [ ON UPDATE action ] }
     [ DEFERRABLE | NOT DEFERRABLE | INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
 where compress_mode can be:
 { DELTA | PREFIX | DICTIONARY | NUMSTR | NOCOMPRESS }