COUNT . , . , DISTINCT . , , :
SELECT Count (snum)
FROM (SELECT DISTINCT snum
FROM Orders)
4
, DISTINCT COUNT Null (.. ).
DISTINCT , , COUNT. MAX MIN, , SUM AVG, , .
COUNT ,
, COUNT , , 5:
SELECT COUNT (*)
FROM Customers;
COUNT NULL .
5
( ) ALL, , DISTINCT, : - .
SELECT Count (snum)
FROM (SELECT all snum
FROM Orders);
ALL Null .
, . . ( , DISTINCT .) , ( blnc) . , . :
SELECT MAX (blnc + (amt))
FROM Orders;
, blnc amt .
GROUP BY
GROUP BY , . SELECT.
, . , MAX (amt) snum. GROUP BY, , :
SELECT snum, MAX (amt)
FROM Orders
GROUP BY snum;
|
|
6.
6
GROUP BY . . , . , , MAX , :
SELECT snum, odate, MAX (amt)
FROM Orders
GROUP BY snum, odate;
7.
7
, , , .
HAVING
, , 3000 . WHERE, , . - :
SELECT snum, odate, MAX (amt)
FROM Oreders
WHERE MAX (amt) > 3000
GROUP BY snum, odate;
3000, HAVING. HAVING , WHERE .
:
SELECT snum, odate, MAX (amt)
FROM Orders
GROUP BY snum, odate
HAVING MAX (amt) > 3000;
8.
8
HAVING , SELECT, GROUP BY. . :
SELECT snum, MAX (amt)
FROM Orders
GROUP BY snum
HAVING odate =# 10/03/1988#;
date HAVING, ( ) . , HAVING GROUP BY. ( 9):
SELECT snum, MAX (amt)
FROM Orders
WHERE odate = #10/03/1990#
GROUP BY snum;
9 3
odate , , . - - " - 3 ."
, HAVING . , - , GROUP BY . , Serres Rifkin:
SELECT snum, MAX (amt)
FROM Orders
GROUP BY snum
HAVING snum IN (1002, 1007);
10.
10 HAVING GROUP BY
|
|