. , , .
, , . , . . . , , . . .
RANGE. , , ,
RANGE IS
, . . , , _ , ._.
(Well-Formed Formula, WFF) , . WFF .
WFF , ( ). , .
._ = 2934
._ = ._
, WFF, WFF, , .
WFF NOT, AND, OR IF... THEN) (NOT > AND > OR) .
WFF (EXISTS) (FORALL).
, WFF, . , , WFF, , .
, .
, . R n - a1, a2,..., an, R (ai1: vi1, ai2: vi2,..., aim: vim) (m <= n), vij , . true , R , .
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() , .
() , .
, .. A B, .
A B, A B.
A B, , A, B.
.
(A B) , A B.
( ) .
SQL-92
SQL-92 SQL. ANSI SQL .
(data definition language DDL) , ..; :
- CREATE TABLE .
- ALTER TABLE .
- DROP TABLE .
- CREATE INDEX .
- ALTER INDEX .
- DROP INDEX .
(data manipulation language DML) , :
- INSERT .
- UPDATE .
- DELETE .
(data query language DQL) ( ) :
SELECT
(data control language DCL) , :
GRANT .
REVOKE .
(transaction processing language TPL) , DML, :
- BEGIN TRANSACTION .
- COMIT TRANSACTION .
- SAVE TRANSACTION .
(cursor control language CCL) : DECLARE CURSOR, FETCH INTO UPDATE WHERE CURRENT.
; . , .