, . , . , SELECT * . , EXISTS, 12.
, , , SELECT . , IN. , = ( 10.6):
SELECT *
FROM Customers
WHERE cnum = (SELECT snum + 1000
FROM Salespeople
WHERE sname = 'Serres');
=============== SQL Execution Log ============
| SELECT * |
| FROM Customers |
| WHERE cnum = |
| (SELECT snum + 1000 |
| WHERE Salespeople |
| WHERE sname = 'Serres' |
| ============================================= |
| cnum cname city rating snum |
| ----- -------- ---- ------ ----- |
| 2002 Giovanni Rome 200 1003 |
===============================================
10.6. .
, cnum 1000, snum Serres. , sname ( UNIQUE INDEX, 17, UNIQUE, 18), . snum num , , .
HAVING
HAVING. , GROUP BY HAVING. ( 10.7):
SELECT rating, COUNT (DISTINCT cnum)
FROM Customers
GROUP BY rating
HAVING rating > (SELECT AVG (rating)
FROM Customers
WHERE city = 'San Jose');
=============== SQL Execution Log ============
| SELECT rating,count (DISTINCT cnum) |
| FROM Customers |
| GROUP BY rating |
| HAVING rating > |
| (SELECT AVG (rating) |
| FROM Customers |
| WHERE city = 'San Jose' |
|===============================================|
| rating |
| -------- -------- |
| 300 2 |
===============================================
10.7. San Jose.
San Jose. 300, , .
. , , . , IN, WHERE, HAVING .
|
|
, . 11, , . , 12 13, , , IN, , .
SQL
1. , Cisneros. , , cnum.
2. , , .
3. , , , .
(. A .)
, , 10 . , WHERE HAVING. , , , .