, SELECT * .
, . , . , , , , .
( 9.3):
SELECT a.cnum, b.cnum, c.cnum
FROM Customers a, Customers b, Customers c
WHERE a.rating = 100 AND b.rating = 200 AND c.rating = 300;
=============== SQL Execution Log ==============
| cnum cnum cnum |
| ----- ------ ------ |
| 2001 2002 2004 |
| 2001 2002 2008 |
| 2001 2003 2004 |
| 2001 2003 2008 |
| 2006 2002 2004 |
| 2006 2002 2008 |
| 2006 2003 2004 |
| 2006 2003 2008 |
| 2007 2002 2004 |
| 2007 2002 2008 |
| 2007 2003 2004 |
| 2007 2003 2008 |
=================================================
9.3. .
, , 100, 200, 300. . GROUP BY ORDER BY, .
, FROM , SELECT. , , . , , Serres (snum 1002) ( 9.4):
SELECT b.cnum, b.cname
FROM Customers a, Customers b
WHERE a.snum = 1002
AND b.city = a.city;
=============== SQL Execution Log ============
| SELECT b.cnum, b.cname |
| FROM Customers a, Customers b |
| WHERE a.snum = 1002 |
| AND b.city = a.city; |
| ==============================================|
| cnum cname |
| ------ --------- |
| 2003 Liu |
| 2008 Cisneros |
| 2004 Grass |
===============================================
9.4. Serres.
a , snum = 1002. , , Serres. b , a; , b , a.
b a, . , Serres , , a . , Serres, Liu Grass. b (San Jose Berlin ) , , Liu Grass.
|
|
, . : . , ( 9.5):
SELECT sname, Salespeople.snum, first.cname, second.cname
FROM Customers first, Customers second, Salespeople
WHERE first.snum = second.snum
AND Salespeople.snum = first.snum
AND first.cnum < second.cnum;
=============== SQL Execution Log ==================
| SELECT cname, Salespeople.snum, first.cname |
| second.cname |
| FROM Customers first, Customers second, Salespeople |
| WHERE first.snum = second.snum |
| AND Salespeople.snum = first.snum |
| AND first.cnum < second.cnum; |
| ====================================================|
| cname snum cname cname |
| ------ ------ -------- -------- |
| Serres 1002 Liu Grass |
| Peel 1001 Hoffman Clemens |
=====================================================
9.5. .
. Interbase 'second' .
, , . . , ( , ). , , , .
, , , . SQL, 10 .
SQL
1. , , . , , .
2. , , , , .
3. , (cname) (city) (rating) Hoffman. , cnum Hoffman, , , , .
(. A .)