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1 | 1 | <!-- |
2 | | -$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.22 2005/05/02 01:52:50 neilc Exp $ |
| 2 | +$PostgreSQL: pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.23 2005/09/22 23:56:46 momjian Exp $ |
3 | 3 | PostgreSQL documentation |
4 | 4 | --> |
5 | 5 |
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@@ -48,10 +48,13 @@ where <replaceable class="PARAMETER">constraint</replaceable> is: |
48 | 48 | </para> |
49 | 49 |
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50 | 50 | <para> |
51 | | - Domains are useful for abstracting common fields between tables into |
52 | | - a single location for maintenance. For example, an email address column may be used |
53 | | - in several tables, all with the same properties. Define a domain and |
54 | | - use that rather than setting up each table's constraints individually. |
| 51 | + Domains are useful for abstracting common fields between tables |
| 52 | + into a single location for maintenance. For example, an email address |
| 53 | + column may be used in several tables, all with the same properties. |
| 54 | + Define a domain and use that rather than setting up each table's |
| 55 | + constraints individually. <note>Keep in mind also that declaring a |
| 56 | + function result value as a domain is pretty dangerous, because none of |
| 57 | + the PLs enforce domain constraints on their results.</note> |
55 | 58 | </para> |
56 | 59 | </refsect1> |
57 | 60 |
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