Learning SQL by Alan Beaulieu

Author:Alan Beaulieu [Alan Beaulieu]
Language: eng
Format: epub
Tags: COMPUTERS / Database Management / Data Mining
ISBN: 9780596555580
Publisher: O'Reilly Media
Published: 2009-04-10T16:00:00+00:00

In some cases, the all operator is a bit more natural. The next example uses all to find accounts having an available balance smaller than all of Frank Tucker’s accounts:

mysql> SELECT account_id, cust_id, product_cd, avail_balance -> FROM account -> WHERE avail_balance < ALL (SELECT a.avail_balance -> FROM account a INNER JOIN individual i -> ON a.cust_id = i.cust_id -> WHERE i.fname = 'Frank' AND i.lname = 'Tucker'); +------------+---------+------------+---------------+ | account_id | cust_id | product_cd | avail_balance | +------------+---------+------------+---------------+ | 2 | 1 | SAV | 500.00 | | 5 | 2 | SAV | 200.00 | | 10 | 4 | CHK | 534.12 | | 11 | 4 | SAV | 767.77 | | 14 | 6 | CHK | 122.37 | | 19 | 8 | SAV | 387.99 | | 21 | 9 | CHK | 125.67 | | 25 | 10 | BUS | 0.00 | +------------+---------+------------+---------------+ 8 rows in set (0.17 sec)

Here’s the data returned by the subquery, which consists of the available balance from each of Frank’s accounts:

mysql> SELECT a.avail_balance -> FROM account a INNER JOIN individual i -> ON a.cust_id = i.cust_id -> WHERE i.fname = 'Frank' AND i.lname = 'Tucker'; +---------------+ | avail_balance | +---------------+ | 1057.75 | | 2212.50 | +---------------+ 2 rows in set (0.01 sec)

Frank has two accounts, with the lowest balance being $1,057.75. The containing query finds all accounts having a balance smaller than any of Frank’s accounts, so the result set includes all accounts having a balance less than $1,057.75.

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