From 24a1fafc8d17375f1296a6dd7e1d213f3d640b2c Mon Sep 17 00:00:00 2001
From: Bruce Momjian <bruce@momjian.us>
Date: Wed, 19 May 2004 23:10:43 +0000
Subject: [PATCH] Clearify CHECK handling of unknown test values.
Karl O. Pinc
---
doc/src/sgml/ref/create_table.sgml | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml
index 771919f1646..511aacc73f3 100644
--- a/doc/src/sgml/ref/create_table.sgml
+++ b/doc/src/sgml/ref/create_table.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/create_table.sgml,v 1.80 2004/03/22 16:18:50 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/create_table.sgml,v 1.81 2004/05/19 23:10:43 momjian Exp $
PostgreSQL documentation
-->
@@ -383,10 +383,13 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> is:
<para>
The <literal>CHECK</> clause specifies an expression producing a
Boolean result which new or updated rows must satisfy for an
- insert or update operation to succeed. A check constraint
- specified as a column constraint should reference that column's
- value only, while an expression appearing in a table constraint
- may reference multiple columns.
+ insert or update operation to succeed. Expressions evaluating
+ to TRUE or UNKNOWN succeed. Should any row of an insert or
+ update operation produce a FALSE result an error exception is
+ raised and the insert or update does not alter the database. A
+ check constraint specified as a column constraint should
+ reference that column's value only, while an expression
+ appearing in a table constraint may reference multiple columns.
</para>
<para>
--
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