Summary

•You can use SQL functions to define, operate, and control data.

•To search for data, use a SELECT statement.

•To specify a condition, use a WHERE phrase.

•To insert, update, and delete data, use INSERT, UPDATE, and DELETE statements.

•To create a table, use a CREATE TABLE statement.

Answers

Q1

SELECT *

FROM export_destination

WHERE population>=100;

Q2

SELECT *

FROM export_destination

WHERE population<100;

Q3

SELECT *

FROM export_destination

WHERE export_destination_code<20

AND population>=100;

Q4

SELECT *

FROM export_destination

WHERE export_destination_code>=30

AND population>100;

None of the countries meet this criteria, so this query returns an empty set.

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Q5

SELECT population

FROM export_destination

WHERE export_destination_name='the Kingdom of Ritol';

Population

150

Q6

SELECT *

FROM export_destination

WHERE export_destination_name LIKE '%n%';

Q7

SELECT MIN(population)

FROM export_destination;

MIN(population)

80

Q8

SELECT MAX(population)

FROM export_destination;

MAX(population)

300

Q9

SELECT SUM(population)

FROM export_destination;

SUM(population)

1,350

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Q10

SELECT SUM(population) FROM export_destination

WHERE export_destination_code>20;

SUM(population)

1,050

Q11

SELECT COUNT(*)

FROM export_destination

WHERE population>=100;

COUNT(*)

7

Q12

SELECT COUNT(*)

FROM export_destination

WHERE district='north sea';

COUNT(*)

3

Q13

SELECT MAX(population)

FROM export_destination

WHERE district='north sea';

MAX(population)

240

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Q14

SELECT SUM(population) FROM export_destination

WHERE NOT(export_destination_name='the Kingdom of Ritol');

SUM(population)

1,200

Q15

SELECT district, AVG(population)

FROM export_destination

GROUP BY district

HAVING AVG(population)>=200;

Q16

SELECT district, COUNT(*)

FROM export_destination

GROUP BY district

HAVING COUNT(*)>=3;

Q17

SELECT *

FROM sales_statement WHERE product_code IN (SELECT product_code FROM product

WHERE unit_price>=300);

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Q18

SELECT *

FROM sales_statement U WHERE quantity< (SELECT AVG(quantity) FROM sales_statement

WHERE product_code=U.product_code);

Q19

INSERT INTO export_destination(export_destination_ code,export_destination_name,population,district) VALUES(12,'the Kingdom of Minanmi',100,'south sea'); INSERT INTO export_destination(export_destination_ code,export_destination_name,population,district) VALUES(15,'the Kingdom of Paronu',200,'middle'); INSERT INTO export_destination(export_destination_ code,export_destination_name,population,district) VALUES(22,'the Kingdom of Tokanta',160,'north sea'); INSERT INTO export_destination(export_destination_ code,export_destination_name,population,district) VALUES(23,'Alpha Empire',120,'north sea');

Q20

CREATE VIEW north_sea_country(export_destination_ code,export_destination_name,population)

AS SELECT export_destination_code,export_destination_name,population FROM export_destination_name

WHERE district='north sea';

Q21

UPDATE export_destination SET population=150

WHERE export_destination_name='the Kingdom of Tokanta';

Q22

DELETE FROM export_destination

WHERE export_destination_name='the Kingdom of Paronu';

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Standardization of SQL

SQL is standardized by the International Organization for Standardization (ISO). In Japan, it is standardized by JIS (Japanese Industrial Standards).

Other SQL standards include SQL92, established in 1992, and SQL99, established in 1999. Relational database products are designed so that queries can be made in accordance with these standards.

Some relational database products have their own specifications. Refer to the operation manual for your database product for further information.

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