.


:




:

































 

 

 

 


, , . ( , , , )




() ( ) . , , SQL.

SQL , . 9: SQL-92.

:

- ;

- ;

- .

. SQL- SELECT FROM.

, () .

, , . , , . .

:

- () ;

- ;

- .

. . , . SELECT.

:

- ;

- ;

- .

( , ) ( WHERE).

ALL, DISTINCT, DISTINCTROW TOP n.

DISTINCT , , . . .

DISTINCTROW DISTINCT , , .

TOP n , .

FROM WHERE GROUP Y, VING ORDER Y .

GROUP Y () .

VING WHERE, GRUP BY .

ORDER BY ASC ( ) DESC ( ).

, , , , :

- ;

- ;

- .

-, . SQL- SELECT FROM c po .

, , (INNER JOIN) (RIGHT JOIN LEFT JOIN).

, , .

. (LEFT JOIN) () , . () , . (RIGHT JOIN) .

, ( ) . SQL- SELECTUNION SELECT. SELECT, , UNION SELECT, . SELECT UNION SELECT. .

AS SELECT.

, ALL UNION , .

. - . SQL- GROUP BY SQL. SQL SELECT SQL, .

SUM() ;

AVG() ;

Min() ;

() . ;

StDev() . - ;

Count() - , ;

Var() .

, , First() Last(paee), (), , . .

SQL- SELECT , , GROUP BY.





:


: 2016-07-29; !; : 749 |


:

:

, .
==> ...

1827 - | 1588 -


© 2015-2024 lektsii.org - -

: 0.01 .