SQLZOO网页中SQL的答案(SELECT from world篇)

SELECT from world篇

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11.

题目:

The CASE statement shown is used to substitute North America forCaribbean in the third column.

Show the name - but substitute Australasia for Oceania - for countries beginning with N.

（翻译：让你给出名字和所属大洲的名字，

              其中所属大洲的名字是Oceania的改成Australasia,

              条件是国名的第一个字符是N）

答案：

            SELECT name,

                          CASE WHEN continent='Oceania' THEN 'Australasia'

                                    ELSE continent  END

            FROM world

            WHERE name LIKE 'N%';

解答：

        CASE有点想IF THEN语句。

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12.

题目：

Show the name and the continent - but substitute Eurasia for Europe and Asia; substitute America - for each country in North America or South America or Caribbean. Show countries beginning with A or B

（翻译：显示name,continent

              要求当continent为Asia和Europe时，修改continent为Eurasia。

                     当continent为North America或South America或Caribbean时，修改为America.

              条件是name以A或B开头）

答案：

SELECT name,
               CASE WHEN continent IN ('Asia','Europe') THEN 'Eurasia'
               WHEN continent IN ('North America','South America','Caribbean') THEN 'America'
                ELSE continent END
FROM world
WHERE name LIKE 'A%' OR name LIKE 'B%'

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答案：

SELECT name,continent,
CASE WHEN continent IN ('Eurasia', 'Turkey')
     THEN 'Europe/Asia'

WHEN continent = 'Oceania' 
     THEN 'Australasia'

WHEN continent = 'Caribbean'
          THEN
          CASE 
          WHEN name LIKE 'B%' 
          THEN 'North America'
          ELSE 'South America'
          END
     ELSE continent 
     END
FROM world
ORDER BY name ASC;