编写高级sql查询

Question

I am working with this schema: http://classes.engr.oregonstate.edu/eecs/winter2013/cs275-400/tester/bsgSchema.html

and I am trying to achieve: Find the fname, lname and ship_instance id of all people who do not have Viper certificaton but are assigned to at least one instance of a Viper class ship (this includes all variants of Viper class ships). Return a row for every ship/person combination.)

I am close. I have written the following query:

SELECT DISTINCT p.fname, p.lname, si.id from bsg_people p
INNER JOIN bsg_ship_assignment sa ON sa.pid = p.id
INNER JOIN bsg_ship_class sc ON sc.id = sa.cid
INNER Join bsg_ship_instance si ON si.class = sa.cid
WHERE p.id NOT
IN (
    SELECT cp.pid
    FROM bsg_cert_people cp
    INNER JOIN bsg_cert c ON c.id = cp.cid
    WHERE cp.cid = '2'
)
AND sc.name = 'viper' 

My query returns a number of extra instances.

Answer 1

SELECT p.fname
     , p.lname
     , sk.id
  FROM bsg_people p 
  LEFT 
  JOIN bsg_cert_people cp  
    ON cp.pid = p.id 
  LEFT 
  JOIN bsg_cert c 
    ON c.id = cp.cid 
   AND c.title = 'viper'
  JOIN bsg_ship_assignment ps
    ON ps.pid = p.id
  JOIN bsg_ship_instance sk
    ON sk.id = ps.sid
   AND sk.class = ps.cid
  JOIN bsg_ship_class k
    ON k.id = sk.class
 WHERE k.name = 'viper'
   AND c.id IS NULL;
+---------+----------+------+
| fname   | lname    | id   |
+---------+----------+------+
| William | Adama    | 8757 |
| Lee     | Adama    |  121 |
| Lee     | Adama    |  289 |
| Lee     | Adama    | 1104 |
| Laura   | Roslin   | 2343 |
| Gaius   | Baltar   |  289 |
| Samuel  | Anders   | 3203 |
| Samuel  | Anders   | 8757 |
| Brendan | Costanza | 7242 |
| Brendan | Costanza | 2343 |
+---------+----------+------+

Answer 2

SELECT bsg_people.fname, bsg_people.lname, bsg_ship_instance.id FROM bsg_people

INNER JOIN bsg_ship_assignment ON bsg_ship_assignment.pid = bsg_people.id

INNER JOIN bsg_ship_instance ON bsg_ship_assignment.sid = bsg_ship_instance.id

INNER JOIN bsg_ship_class ON bsg_ship_class.id = bsg_ship_instance.class

WHERE bsg_people.id NOT IN

(

SELECT bsg_cert_people.pid FROM bsg_cert_people

INNER JOIN bsg_cert ON bsg_cert_people.cid = bsg_cert.id

WHERE bsg_cert.title = 'Viper'

)

AND bsg_ship_class.name = 'viper'