<!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.87 2006/07/04 18:07:24 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.88 2006/08/03 20:57:06 tgl Exp $
PostgreSQL documentation
-->
</para>
<para>
+ The same, when the column has a default expression that won't automatically
+ cast to the new datatype:
+<programlisting>
+ALTER TABLE foo
+ ALTER COLUMN foo_timestamp DROP DEFAULT,
+ ALTER COLUMN foo_timestamp TYPE timestamp with time zone
+ USING
+ timestamp with time zone 'epoch' + foo_timestamp * interval '1 second',
+ ALTER COLUMN foo_timestamp SET DEFAULT now();
+</programlisting>
+ </para>
+
+ <para>
To rename an existing column:
<programlisting>
ALTER TABLE distributors RENAME COLUMN address TO city;
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.198 2006/07/31 20:09:00 tgl Exp $
+ * $PostgreSQL: pgsql/src/backend/commands/tablecmds.c,v 1.199 2006/08/03 20:57:06 tgl Exp $
*
*-------------------------------------------------------------------------
*/
ATSimplePermissions(rel, true);
ATSimpleRecursion(wqueue, rel, cmd, recurse);
/* No command-specific prep needed */
- pass = AT_PASS_ADD_CONSTR;
+ pass = cmd->def ? AT_PASS_ADD_CONSTR : AT_PASS_DROP;
break;
case AT_DropNotNull: /* ALTER COLUMN DROP NOT NULL */
ATSimplePermissions(rel, false);