COUNT(*) , :
COUNT- ,
SUM- ,
AVG- ,
MAX- ,
MIN- .
SQL- .
, COUNT(*), DISTINCT (), , , . COUNT(*) ( ).
GROUP BY, _SELECT SQL- , . , , SQL-.
, , , , (=5), , ,
SELECT SUM(),AVG(),COUNT(),
COUNT(DISTINCT ),COUNT(*)
FROM
WHERE = 5;
39.
, .
SELECT , SUM(_)
FROM
GROUP BY ;
GROUP BY ( ) FROM , , GROUP BY. SELECT. , .. , GROUP BY, , , , SQL-, (, ).
, GROUP BY ORDER BY.
SELECT , SUM(_)
FROM
GROUP BY
ORDER BY ;
HAVING GROUP BY, HAVING .
, , :
| SELECT FROM GROUP BY HAVING COUNT(*) > 2; | |
40. .
SELECT _.*, .*
FROM _, ;
SELECT .*, .*, _.*, .*
FROM , , _,
WHERE . = .
AND . = _.
AND . = .;
:
SELECT , , , , , , , ,
FROM , , _,
WHERE . = .
|
|
|
AND . = _.
AND . = .;
, , , :
SELECT , , , , ' -',
FROM , , _,
WHERE . = .
AND . = _.
AND . = .
AND = ;
SELECT STUDEBT.LNAME, STUDENT.FNAME, STUDENT.SNUM
FROM STUDENT, STUDENT AS S1
WHERE SRUDENT.LNAME=S1.LNAME
AND STUDENT.FNAME=S1.FNAME
AND STUDENT.DOB=S1.DOB
AND STUDENT.SNUM=S1.SNUM
41.-
11.
SELECT ,
FROM
WHERE 11 IN
(SELECT
FROM
WHERE = .);
, . , . , . , :
1. . , 1. . , 1,
(SELECT
FROM
WHERE = 1);
(9, 11, 12, 15). 1. =1 ( ) , =11 , , , .
2. .. , .
42.
- , WHERE (HAVING) SELECT , WHERE . WHERE (HAVING) ..
.
SELECT ,
FROM
WHERE IN
(SELECT
FROM
WHERE = 11);
, , 3 2 ( - INTERSECT):
SELECT P.PNAME
FROM P
WHERE P.STATUS > 3
INTERSECT
SELECT P.PNAME
FROM P, PD
WHERE P.PNUM = PD.PNUM AND
PD.DNUM = 2;
, , 3, , 2 ( - EXCEPT):
SELECT P.PNAME
FROM P
WHERE P.STATUS > 3
EXCEPT
SELECT P.PNAME
FROM P, PD
WHERE P.PNUM = PD.PNUM AND
PD.DNUM = 2;
EXIST
EXISTS (SELECT * FROM...).
, "SELECT * FROM..." , .. - , FROM , WHERE . ( .)
|
|
|
| SELECT FROM WHERE EXISTS (SELECT * FROM WHERE = . AND = 11); |
, ( IN ), EXISTS SQL. , IN, EXISTS. .
SQL , , :
a. , , m;
b. i (i = 1, 2,..., m) i- i- .
, , , = 1:
| SELECT FROM WHERE = 0 UNION SELECT FROM WHERE = 1 |
, UNION.
SELECT WHERE, ORDER BY
45. DELETE.
DELETE
DELETE
FROM SKLAD
[WHERE SKLAD_ID=4;];
( WHERE ) , WHERE .
