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1 | | -<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.92 2010/04/03 07:22:53 petere Exp $ --> |
| 1 | +<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.93 2010/04/06 02:18:04 momjian Exp $ --> |
2 | 2 |
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3 | 3 | <chapter id="ddl"> |
4 | 4 | <title>Data Definition</title> |
@@ -861,7 +861,8 @@ CREATE TABLE order_items ( |
861 | 861 | <para> |
862 | 862 | Exclusion constraints ensure that if any two rows are compared on |
863 | 863 | the specified columns or expressions using the specified operators, |
864 | | - at least one of these operator comparisons will be false. The syntax is: |
| 864 | + at least one of these operator comparisons will return false or null. |
| 865 | + The syntax is: |
865 | 866 | <programlisting> |
866 | 867 | CREATE TABLE circles ( |
867 | 868 | c circle, |
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