,
SELECT '- =',SUM(_),COUNT(_)
FROM
WHERE = 10;
: | ||
'- =' | SUM(_) | COUNT(_) |
- = |
, - , COUNT(*), . , - , COUNT 0, - NULL.
, , , , (=5), , ,
SELECT SUM(),AVG(),COUNT(),
COUNT(DISTINCT ),COUNT(*)
FROM
WHERE = 5;
(*)
SUM() | AVG() | COUNT() | COUNT(DISTINCT ) | COUNT |
6.2 | 1.24 |
, " ?":
SELECT SUM(_),COUNT(_)
FROM
WHER = 2;
:
SUM(_) | COUNT (_) |
-0- |
, (" "):
: | |
SELECT (SUM(_) +AVG()) FROM WHERE = 10; | |
SUM(_)+AVG() | |
220.6 |
2.5.3. GROUP BY
, , . , , .
SELECT , SUM(_)
FROM
GROUP BY ;
. 2.3,.
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|
. 2.3. GROUP BY
|
|
GROUP BY ( ) FROM , , GROUP BY. , = 1, = 2 .. (. . 2.3.). SELECT. , .. , GROUP BY, , , , SQL-, (, ).
, GROUP BY ORDER BY. (. 2.3,)
SELECT , SUM(_)
FROM
GROUP BY
ORDER BY ;
, , . ,
SELECT , , COUNT()
FROM
GROUP BY , ;
, (32 ) :
COUNT() | ||
... |
WHERE GROUP BY, , WHERE, .
, , =2:
SELECT , SUM(_)
FROM
WHERE <> 2
GROUP BY ;
, . 2.3,, (. 2.3,) 15, 5 6.
2.5.4. HAVING
HAVING (.2.3) , WHERE : , , WHERE . GROUP BY, HAVING .
, , :
SELECT FROM GROUP BY HAVING COUNT(*) > 2; | : | |
.3.6 .
3.