Basic Oracle Concepts and Programming Question:

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A subquery can be used with the IN operator as "expression IN (subquery)". The subquery should return a single column with one or more rows to form a list of values to be used by the IN operation. The following tutorial exercise shows you how to use a subquery with the IN operator:

SQL> SELECT first_name, last_name FROM employees
2 WHERE department_id IN (
3 SELECT department_id FROM departments
4 WHERE location_id = 1700
5 );
<pre>FIRST_NAME LAST_NAME
-------------------- -------------------------
Steven King
Neena Kochhar
Lex De Haan
Nancy Greenberg
Daniel Faviet
John Chen
Ismael Sciarra
......</pre>