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<title>ALTER DOMAIN</title>
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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="refentry" lang="en">
<a name="sql-alterdomain"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2>Name</h2>
<p> ALTER DOMAIN
— change the definition of a domain
</p>
</div>
<a name="id741489"></a><div class="refsynopsisdiv">
<h2>Synopsis</h2>
<pre class="synopsis">ALTER DOMAIN <em class="replaceable"><code>name</code></em>
{ SET DEFAULT <em class="replaceable"><code>expression</code></em> | DROP DEFAULT }
ALTER DOMAIN <em class="replaceable"><code>name</code></em>
{ SET | DROP } NOT NULL
ALTER DOMAIN <em class="replaceable"><code>name</code></em>
ADD <em class="replaceable"><code>domain_constraint</code></em>
ALTER DOMAIN <em class="replaceable"><code>name</code></em>
DROP CONSTRAINT <em class="replaceable"><code>constraint_name</code></em> [ RESTRICT | CASCADE ]
ALTER DOMAIN <em class="replaceable"><code>name</code></em>
OWNER TO <em class="replaceable"><code>new_owner</code></em>
ALTER DOMAIN <em class="replaceable"><code>name</code></em>
SET SCHEMA <em class="replaceable"><code>new_schema</code></em>
</pre>
</div>
<div class="refsect1" lang="en">
<a name="id741584"></a><h2>Description</h2>
<p> <code class="command">ALTER DOMAIN</code> changes the definition of an existing domain.
There are several sub-forms:
</p>
<div class="variablelist"><dl>
<dt><span class="term">SET/DROP DEFAULT</span></dt>
<dd><p> These forms set or remove the default value for a domain. Note
that defaults only apply to subsequent <code class="command">INSERT</code>
commands; they do not affect rows already in a table using the domain.
</p></dd>
<dt><span class="term">SET/DROP NOT NULL</span></dt>
<dd><p> These forms change whether a domain is marked to allow NULL
values or to reject NULL values. You may only <code class="literal">SET NOT NULL</code>
when the columns using the domain contain no null values.
</p></dd>
<dt><span class="term">ADD <em class="replaceable"><code>domain_constraint</code></em></span></dt>
<dd><p> This form adds a new constraint to a domain using the same syntax as
<a href="sql-createdomain.html">CREATE DOMAIN</a>.
This will only succeed if all columns using the domain satisfy the
new constraint.
</p></dd>
<dt><span class="term">DROP CONSTRAINT</span></dt>
<dd><p> This form drops constraints on a domain.
</p></dd>
<dt><span class="term">OWNER</span></dt>
<dd><p> This form changes the owner of the domain to the specified user.
</p></dd>
<dt><span class="term">SET SCHEMA</span></dt>
<dd><p> This form changes the schema of the domain. Any constraints
associated with the domain are moved into the new schema as well.
</p></dd>
</dl></div>
<p> You must own the domain to use <code class="command">ALTER DOMAIN</code>.
To change the schema of a domain, you must also have
<code class="literal">CREATE</code> privilege on the new schema.
To alter the owner, you must also be a direct or indirect member of the new
owning role, and that role must have <code class="literal">CREATE</code> privilege on
the domain's schema. (These restrictions enforce that altering the owner
doesn't do anything you couldn't do by dropping and recreating the domain.
However, a superuser can alter ownership of any domain anyway.)
</p>
</div>
<div class="refsect1" lang="en">
<a name="id741721"></a><h2>Parameters</h2>
<p> </p>
<div class="variablelist"><dl>
<dt><span class="term"><em class="replaceable"><code>name</code></em></span></dt>
<dd><p> The name (possibly schema-qualified) of an existing domain to
alter.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>domain_constraint</code></em></span></dt>
<dd><p> New domain constraint for the domain.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>constraint_name</code></em></span></dt>
<dd><p> Name of an existing constraint to drop.
</p></dd>
<dt><span class="term"><code class="literal">CASCADE</code></span></dt>
<dd><p> Automatically drop objects that depend on the constraint.
</p></dd>
<dt><span class="term"><code class="literal">RESTRICT</code></span></dt>
<dd><p> Refuse to drop the constraint if there are any dependent
objects. This is the default behavior.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>new_owner</code></em></span></dt>
<dd><p> The user name of the new owner of the domain.
</p></dd>
<dt><span class="term"><em class="replaceable"><code>new_schema</code></em></span></dt>
<dd><p> The new schema for the domain.
</p></dd>
</dl></div>
<p>
</p>
</div>
<div class="refsect1" lang="en">
<a name="id741817"></a><h2>Examples</h2>
<p> To add a <code class="literal">NOT NULL</code> constraint to a domain:
</p>
<pre class="programlisting">ALTER DOMAIN zipcode SET NOT NULL;
</pre>
<p>
To remove a <code class="literal">NOT NULL</code> constraint from a domain:
</p>
<pre class="programlisting">ALTER DOMAIN zipcode DROP NOT NULL;
</pre>
<p>
</p>
<p>
To add a check constraint to a domain:
</p>
<pre class="programlisting">ALTER DOMAIN zipcode ADD CONSTRAINT zipchk CHECK (char_length(VALUE) = 5);
</pre>
<p>
</p>
<p>
To remove a check constraint from a domain:
</p>
<pre class="programlisting">ALTER DOMAIN zipcode DROP CONSTRAINT zipchk;
</pre>
<p>
</p>
<p> To move the domain into a different schema:
</p>
<pre class="programlisting">ALTER DOMAIN zipcode SET SCHEMA customers;
</pre>
<p>
</p>
</div>
<div class="refsect1" lang="en">
<a name="sql-alterdomain-compatibility"></a><h2>Compatibility</h2>
<p> <code class="command">ALTER DOMAIN</code> conforms to the <acronym class="acronym">SQL</acronym>
standard,
except for the <code class="literal">OWNER</code> and <code class="literal">SET SCHEMA</code> variants,
which are <span class="productname">PostgreSQL</span> extensions.
</p>
</div>
<div class="refsect1" lang="en">
<a name="sql-alterdomain-see-also"></a><h2>See Also</h2>
<span class="simplelist"><a href="sql-createdomain.html">CREATE DOMAIN</a>, <a href="sql-dropdomain.html">DROP DOMAIN</a></span>
</div>
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