SQL , .. , , SQL- . , SQL , , , .
SQL :
- , SQL ;
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- SQL , , . , SQL ;
- SQL , ;
- SQL , . SQL , , , , , ;
- SQL , . , , , ;
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, , . , , .. , . SQL .
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SQL , , . - . , , , . SQL . , SQL-. SQL- . SQL . , , , . , SQL . , . , . SQL , , .
SQL , . SQL SQL-. , . , .
SQL (, Remote Data Access, RDA). , . , . , : (OnLine Transaction Processing, OLTP) (OnLine Analytical Processing, OLAP). , , - , .
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SQL SELECT. SELECT () . () SELECT .., .. . , SELECT "" SQL.
SELECT :
- , ();
- WHERE- HAVING- ( , " ");
- CREAT VIEW, DECLARE CURSOR INSERT;
- (INTO-).
:
- (*) "" - , .. " , ";
- ([]) , , , (.. );
- ({}) , , , , .. , , SQL;
- (...) , ;
- (|) . ASC|DESC , ASC DESC; , , (, [ASC]|DESC , ASC);
- (;) SQL;
- (,) ;
- () SQL;
- SQL ( ) , ;
- , , , (_);
- , ,... ( ) _, _,..., ;
- , _, ; ( ) () _ ().
SELECT () :
SELECT [[ALL] | DISTINCT]{ * | _SELECT
[,_SELECT]...}
FROM {_ | } []
[,{_ | } []]...
[WHERE ]
[GROUP BY [HAVING ]];
:
- SELECT - () ( ) ()
- FROM - () ,
- WHERE - ()
- GROUP BY - ( ) , , SELECT SQL- SUM (), COUNT (), MIN ( ), MAX ( ) AVG ( )
- HAVING - () ,
WHERE :
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WHERE [NOT] WHERE_
[[AND|OR][NOT] WHERE_]...
: WHERE_ :
{ = | <> | < | <= | > | >= }
{ | () }
_1 [NOT] BETWEEN _2 AND _3
[NOT] IN { ( [,]...)
| () }
IS [NOT] NULL
[.] [NOT] LIKE '_'
(= | <> | < | <= | > | >=) WHERE BETWEEN (), LIKE ( ), IN (), IS NULL ( ) EXISTS (), NOT (). , :
- AND - AND ;
- OR - OR ;
- AND NOT - ;
- OR NOT - ;
- AND OR ( AND OR). WHERE , .
, , , ASCII. , , , .
GROUP BY
GROUP BY [.] [,[.]]...
[HAVING ]
GROUP BY , , GROUP BY. , SELECT, (, ..).
HAVING ( WHERE)
HAVING [NOT] HAVING_
[[AND|OR][NOT] HAVING_]...
, .
