SQL ZOO 练习 —— SELECT basics

网址： https://sqlzoo.net/wiki/SELECT_Quiz

一、STUDY 学习篇

1.The example uses a WHERE clause to show the population of ‘France’. Note that strings (pieces of text that are data) should be in ‘single quotes’;

Modify it to show the population of Germany

SELECT population FROM world WHERE name = 'Germany'

2. Checking a list The word IN allows us to check if an item is in a list. The example shows the name and population for the countries ‘Brazil’, ‘Russia’, ‘India’ and ‘China’.

Show the name and the population for ‘Sweden’, ‘Norway’ and ‘Denmark’.

SELECT name, population FROM world
  WHERE name IN ('Sweden', 'Norway', 'Denmark');

3.Which countries are not too small and not too big? BETWEEN allows range checking (range specified is inclusive of boundary values). The example below shows countries with an area of 250,000-300,000 sq. km.

Modify it to show the country and the area for countries with an area between 200,000 and 250,000.

SELECT name, area FROM world
  WHERE area BETWEEN 200000 AND 250000

二、QUIZ 测验篇

1.Select the code which produces this table

SELECT name, population
  FROM world
 WHERE population BETWEEN 1000000 AND 1250000

2.Pick the result you would obtain from this code:

      SELECT name, population
      FROM world
      WHERE name LIKE "Al%"

3. Select the code which shows the countries that end in A or L

SELECT name FROM world
 WHERE name LIKE '%a' OR name LIKE '%l'

4.Pick the result from the query

SELECT name,length(name)
FROM world
WHERE length(name)=5 and region='Europe'

5. Here are the first few rows of the world table:

Pick the result you would obtain from this code:

SELECT name, area*2 FROM world WHERE population = 64000

6.Select the code that would show the countries with an area larger than 50000 and a population smaller than 10000000

SELECT name, area, population
  FROM world
 WHERE area > 50000 AND population < 10000000

7. Select the code that shows the population density of China, Australia, Nigeria and France

SELECT name, population/area
  FROM world
 WHERE name IN ('China', 'Nigeria', 'France', 'Australia')