Without using conjunctions in conditions of selection operators
<p>Let's say there is a table call ITEM and it contains 3 attributes(name, id, price):</p>

<pre><code>name      id      price

Apple     1       3
Orange    1       3
Banana    2       4
Cherry    3       5
Mango     1       3
</code></pre>

<p>How should I write a query to use a constants selection operator to select those item that have same prices and same ids ? The first thing come into my mind is use a rename operator to rename id to id', and price to price', then union it with the ITEM table,  but since I need to select 2 tuples (price=price' &amp; id=id') from the table, how can I select them without using the conjunctions operator in relational algebra ?</p>

<p>Thank you.</p>