| 1. | . |
, , . . , . , , . , , , . CREATE VIEW.
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CREATE VIEW
AS SELECT * FROM
WHERE = 2;
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SELECT * FROM
WHERE > 1200000;
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SELECT * FROM
WHERE = 2
AND > 1200000;
SQL , , f GROUP BY . , , , , :
CREATE VIEW
AS SELECT , COUNT(DISTINCT )
FROM GROUP BY ;
:
SELECT * FROM ;
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CREATE VIEW
AS SELECT ,a. As ,,,,,,c. As
FROM a, b, c
WHERE a. = b.
AND b. = c.;
SELECT * FROM
WHERE = ;
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SELECT a.sname, cname, ame*comm.
FROM a, b
WHERE a. =
AND b. = a.;
, . , , . :
CREATE VIEW Esf
AS SELECT , ,
FROM
WHERE = (
SELECT MAX()
FROM );
SELECT * FROM Esf;
DROP VIEW < >.
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| 2. | . |
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| 4. | DISTINCT . |
| 5. | GROUP BY HAVING . |
| 6. | . |
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| 8. | , . |
| 9. | INSERT , NOT NULL. |
, , . , . :
CREATE VIEW Highrating
AS SELECT cnum, rating FROM Customers
WHERE rating = 300;
:
INSERT INTO Highrating
VALUES (2000, 200);
. SQL : :
WITH CHECK OPTION
. . . , , , :
CREATE VIEW Londonstaff
AS SELECT cnum, cname, comm
FROM Salespeople
WHERE city =London;
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, city. :
SELECT snum, sname
FROM Londonstaff;
WITH CHECK OPTION , , , . :
CREATE VIEW Highrating
AS SELECT cnum, rating FROM Customers
WHERE rating = 300
WHITH CHECK OPTION;
, 300 , :
CREATE VIEW Vyrating
AS SELECT *
FROM Highrating;
UPDATE Murating
SET rating = 200
WHERE cnum = 2004;
ER-
| 3. | - |
"" (entityrelation, ERmethod) . . , ( ) , (). , .
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