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+$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.24 2001/05/09 13:27:15 momjian Exp $
Postgres documentation
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</para>
<para>
- In the current implementation, only FOREIGN KEY constraints can
+ In the current implementation, only FOREIGN KEY and CHECK constraints can
be added to a table. To create or remove a unique constraint, create
a unique index (see <xref linkend="SQL-CREATEINDEX"
- endterm="SQL-CREATEINDEX-title">). To add check constraints
- you need to recreate and reload the table, using other
- parameters to the <xref linkend="SQL-CREATETABLE"
- endterm="SQL-CREATETABLE-title"> command.
+ endterm="SQL-CREATEINDEX-title">).
</para>
<para>
</programlisting>
</para>
+ <para>
+ To add a check constraint to a table:
+ <programlisting>
+ALTER TABLE distributors ADD CONSTRAINT zipchk CHECK (char_length(zipcode) = 5)
+ </programlisting>
+ </para>
+
<para>
To add a foreign key constraint to a table:
<programlisting>