This patch fixes a minor inaccuracy in the documentation: NOT NULL is

not synonymous with CHECK (xxx IS NOT NULL) -- for example, consider
ALTER TABLE ADD PRIMARY KEY, which checks for 'NOT NULL', not a check
constraint.

Neil Conway

diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 5ef7a5d6e70518da72c93682636e0550efda21ff..9e9525775c7173ab87853a76c5aa4b4e8bc7c62f 100644 (file)
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1,5 +1,5 @@
 
 
@@ -247,9 +247,7 @@ and table_constraint is:
     NOT NULL
     
      
-      The column is not allowed to contain NULL values.  This is
-      equivalent to the column constraint CHECK (
-      class="PARAMETER">column NOT NULL).
+      The column is not allowed to contain NULL values.