Document that zero-column tables are allowed (and non-standard).

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index 8c4d6980feda581703b4b4093ae3091afdde2f25..a8cbfb5bc68030b3d6d940984ebc2ab5b907f4b8 100644 (file)
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -1,5 +1,5 @@
 
 
@@ -506,6 +506,12 @@ ALTER TABLE distributors ADD PRIMARY KEY (dist_id);
     The clauses to rename tables, columns, indexes, and sequences are
     PostgreSQL extensions from SQL92.
    
+
+   
+    ALTER TABLE DROP COLUMN can be used to drop the only column
+    of a table, leaving a zero-column table.  This is an extension from SQL92,
+    which disallows zero-column tables.
+   
  
   
  

diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 6d67f22a6b9261978d2c414b9635a8f6c627b011..db51a26469faa650949188494e832b5d00b12bed 100644 (file)
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1,5 +1,5 @@
 
 
@@ -915,6 +915,19 @@ CREATE ASSERTION name CHECK ( condition<
     standard.
    
   
+
+  
+   Zero-column tables
+
+   
+    PostgreSQL allows a table of no columns
+    to be created (for example, CREATE TABLE foo();).  This
+    is an extension from the SQL standard, which does not allow zero-column
+    tables.  Zero-column tables are not in themselves very useful, but
+    disallowing them creates odd special cases for ALTER TABLE
+    DROP COLUMN, so it seems cleaner to ignore this spec restriction.
+   
+