.
1. . , .
2. "", "", "" = # ( ), >, <, >=, <=.
3. , . . , , .
4. - , . , "", "", "", , , = "" <= .
5. , . . . ) , .
ALPHA QUEL. (range)
range of <> is <><>
:
some, ( );
all, ( ).
(get)
get <> (< >) where <>.
. "", "", "".
:
range of Z is some.
Z (some - ) .
range of W is all.
W (all - ) .
" " :
range of Z is some
get W () where ._=._
and .="".
SQL ( ). SQL Select - From, Where, Group by, Having, Order by.
Select *, . From . , . Where , . (=,> ..), All, Any, Between, Exists, Like, In . Group by -. Having , Group by. Order by , .
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" "
Select
From ,
Where .="" '
. . , (, , )
(513,"",800)
(155,"",600)
(247,"",600)
- , , , _ , .
, " 600" goal ()
Goal: (,_,600)
=155
=247.
. , .
(, , ) .
. 3.8 .
, , - (). , . , , . 3.9. .
. "" , , ( ) .
W(R,S) , R, S , .
, . .
.
.
, :
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- ,
,
;
.
, .
, . . , , .
( ):
-,
, .