Performing intersection without intersect operator - Mailing list pgsql-sql

<div dir="ltr">Hi all,<br /><br />I want to perform an intersection between several select queries but without using
theINTERSECT keyword.<br /><br />select userid from orders where productid=1 INTERSECT select userid from orders where
productid=2<br/><br />I want to transform it without the INTERSECT.<br /><br />Thanks to all<br /><br />Nacef<br
/></div>