Use Subqueries in the FROM Clause in Oracle

Q

How To Use Subqueries in the FROM Clause in Oracle?

✍: FYIcenter.com

A

If you have a query returning many rows of data, and you want to perform another query on those rows, you can put the first query as a subquery in the FROM clause of the second query. The following statement shows you how to use a subquery as base table for the main query:

SQL> SELECT * FROM (
  2    SELECT first_name, last_name, department_name
  3    FROM employees e, departments d 
  4    WHERE e.department_id = d.department_id
  5  ) WHERE department_name LIKE 'S%' ORDER BY last_name;
FIRST_NAME        LAST_NAME              DEPARTMENT_NAME
----------------- ---------------------- ---------------
Ellen             Abel                   Sales
Sundar            Ande                   Sales
Mozhe             Atkinson               Shipping
Amit              Banda                  Sales
Elizabeth         Bates                  Sales
Sarah             Bell                   Shipping
......

 

Counting Groups Returned with the GROUP BY Clause in Oracle

Use Subqueries with the EXISTS Operator in Oracle

Understanding SQL SELECT Query Statements in Oracle

⇑⇑ Oracle Database Tutorials

2019-09-27, 1566🔥, 0💬