doc: Add PERIOD to ALTER TABLE reference docs

Commit 89f908a6d0a documented foreign keys with PERIOD in the CREATE
TABLE docs, but not in ALTER TABLE.  This commit adds the new syntax
to the ALTER TABLE docs.

Author: Paul A. Jungwirth 
Discussion: https://www.postgresql.org/message-id/57ea0668-5205-426e-b934-efc89f2186c2@illuminatedcomputing.com

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index ff7f4e43f0b2c7ffde694c4ae11075726bcb429b..c8f7ab7d9563145c3be08fedcf407002c5439490 100644 (file)
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -118,7 +118,7 @@ WITH ( MODULUS numeric_literal, REM
   UNIQUE [ NULLS [ NOT ] DISTINCT ] ( column_name [, ... ] [, column_name WITHOUT OVERLAPS ] ) index_parameters |
   PRIMARY KEY ( column_name [, ... ] [, column_name WITHOUT OVERLAPS ] ) index_parameters |
   EXCLUDE [ USING index_method ] ( exclude_element WITH operator [, ... ] ) index_parameters [ WHERE ( predicate ) ] |
-  FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ]
+  FOREIGN KEY ( column_name [, ... ] [, PERIOD column_name ] ) REFERENCES reftable [ ( refcolumn [, ... ]  [, PERIOD refcolumn ] ) ]
     [ MATCH FULL | MATCH PARTIAL | MATCH SIMPLE ] [ ON DELETE referential_action ] [ ON UPDATE referential_action ] }
 [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]