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SQL




SQL , , , CREATE (). . , , , . , WHERE(). , . , . . 1 18 , . .

SQL.

CHAR()     VARCHAR()     SMALLINT INT DEC(.,)   FLOAT ()     REAL   DOUBLE PRECISION DATE . .   | |   | |

(62.3)

(1.57)

('')

(Null)

- , , ,

:

1) : +, -, *, /

2) : =, >, <, >=, <=, <>

3) : AND, OR, NOT

4) : IN ( , ), BETWEEN ( , ), LIKE ( ), IS NULL ( NULL-)

* (__ + - )

52. SQL (Structured Query Language) .

SQL , , , .

SQL : .

SQL , , . , , SQL .

SQL , :

, ;

;

;

;

;

/;

- ;

.

SQL:

SQL . SQL , ;

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SQL . SQL ;

SQL /. SQL , .

 

55. SQL, SQL:2003, SQL:1999 , . . , SQL, (entry), (intermediate) (full) . , .

, , .

CREATE TABLE ( INT, CHAR(15), INT, CHAR(3))

DROP TABLE

ALTER TABLE ( CHAR(10))

CREATE VIEW 1 AS SELECT *FROM WHERE = "-1"

, , .

INSERT INTO VALUES (980101, " . .", 1980, "")

DELETE FROM WHERE =980201

UPDATE SET = " . ." WHERE =980201

SELECT.

SELECT * FROM WHERE =" . ." OR =" . ."

 

 

54. SQL () . SELECT () , . . SELECT CREATE- , INSERT -, DELETE - , COMMIT ...

FROM , SELECT, . , , . , 1 18 , .

WHERE , , , , .

ORDER BY (Asc , Desc . , ).

CHAR() HARACTER()

INTEGER INT

SMALLINT

NUMERIC(, ) DECIMAL(, DEC(, )

FLOAT ()

Double precision

SQL , . , , , .

. , : 21 -375.18 62.3

, : 1.57 -3.149 2.5-6 0.78324

. : '' 'New York' ' . .'

(NULL). SQL .

SQL- () . :

COUNT ;

SUM ;

AVG ;

MAX ;

MIN .

:

: + (), - (), * (), / ();

: = (), > (), < (), >= ( ), <= ( ), <> ( );

: AND ( ""), OR ( ""), NOT ( );

 

 

56. .

SQL- SQL, .

SQL COMMIT ROLLBACK. , . COMMIT . , , . ROLLBACK . , , , . , .

COMMIT ROLLBACK , .

 

 

57. , () . .

, . : , . :

SELECT ;

INSERT ;

UPDATE ;

DELETE ;

REFERENCES .

 

58 .. , , .

 

 





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