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PostgreSQL documentation

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Usage

</title>

<para>

To add a NOT NULL constraint to acolumn:

To add a NOT NULL constraint to adomain:

<programlisting>

ALTER DOMAIN zipcode SET NOT NULL;

</programlisting>

To remove a NOT NULL constraint from acolumn:

To remove a NOT NULL constraint from adomain:

<programlisting>

ALTER DOMAIN zipcode DROP NOT NULL;

</programlisting>

</para>

<para>

To add a check constraint to atable:

To add a check constraint to adomain:

<programlisting>

ALTER DOMAIN zipcode ADD CONSTRAINT zipchk CHECK (char_length(VALUE) = 5);

</programlisting>

</para>

<para>

To remove a check constraint from atable and all its children:

To remove a check constraint from adomain:

<programlisting>

ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;

</programlisting>