<varlistentry>

<term>

<literal>{ ERROR | NULL | DEFAULT <replaceable>expression</replaceable> } ON EMPTY</literal>

<literal>{ ERROR | NULL | DEFAULT <replaceable class="parameter">expression</replaceable> } ON EMPTY</literal>

</term>

<listitem>

<para>

Defines the return value if no JSON value is found. The default is <literal>NULL</literal>.

If you use <literal>DEFAULT <replaceable>expression</replaceable></literal>, the provided

<replaceable>expression</replaceable> is evaluated and cast to the type specified in the

<command>RETURNING</command> clause.

Defines the return value if no JSON value is found. The default is

<literal>NULL</literal>. If you use

<literal>DEFAULT <replaceable class="parameter">expression</replaceable></literal>,

the provided <replaceable class="parameter">expression</replaceable> is

evaluated and cast to the type specified in the <command>RETURNING</command> clause.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>

<literal>{ ERROR | NULL | DEFAULT <replaceable>expression</replaceable> } ON ERROR</literal>

<literal>{ ERROR | NULL | DEFAULT <replaceable class="parameter">expression</replaceable> } ON ERROR</literal>

</term>

<listitem>

<para>

Defines the return value if an unhandled error occurs. The default is <literal>NULL</literal>.

If you use <literal>DEFAULT <replaceable>expression</replaceable></literal>, the provided

<replaceable>expression</replaceable> is evaluated and cast to the type specified in the

<command>RETURNING</command> clause.

Defines the return value if an unhandled error occurs. The default is

<literal>NULL</literal>. If you use

<literal>DEFAULT <replaceable class="parameter">expression</replaceable></literal>,

the provided <replaceable class="parameter">expression</replaceable> is

evaluated and cast to the type specified in the <command>RETURNING</command> clause.

</para>

</listitem>

</varlistentry>