sqlzoo 0.SELECT basics 1.SELECT name 2.SELECT from World 答案

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Original title link: https://sqlzoo.net/

Other question solution links: https://blog.csdn.net/aiqiyizz/article/details/109057732

The solution corresponds to the English version.

The previous questions are not difficult, so they can be integrated into one, and then the catalog query is enough.

I wanted to put together a few more sections, but the amount seems to be quite large, so let's do it.

0 SELECT basics

0.1 Introducing the world table of countries

SELECT population FROM world
  WHERE name = 'Germany'

0.2 Scandinavia

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

0.3 Just the right size

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

1 SELECT names

1.1 Pattern Matching Strings

SELECT name FROM world
  WHERE name LIKE 'Y%'

1.2

SELECT name FROM world
  WHERE name LIKE '%y'

1.3

SELECT name FROM world
  WHERE name LIKE '%x%'

1.4

SELECT name FROM world
  WHERE name LIKE '%land'

1.5

SELECT name FROM world
  WHERE name LIKE 'C%ia'

1.6

SELECT name FROM world
  WHERE name LIKE '%oo%'

1.7

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

1.8

SELECT name FROM world
 WHERE name LIKE '_t%'
ORDER BY name

1.9

SELECT name FROM world
 WHERE name LIKE '%o__o%'

1.10

SELECT name FROM world
 WHERE name LIKE '____'

Regular expression

SELECT name FROM world
 WHERE name REGEXP '^.\{4\}$'

1.11 Harder Questions

SELECT name
  FROM world
 WHERE capital = name

1.12

SELECT name
  FROM world
 WHERE capital LIKE concat(name, ' City')

1.13

SELECT capital, name
  FROM world
 WHERE capital LIKE CONCAT('%', name, '%')

1.14

SELECT capital, name
  FROM world
 WHERE capital LIKE CONCAT(name, '%')
       AND capital <> name

1.15

SELECT name, REPLACE(capital, name, '')
FROM world
WHERE capital LIKE CONCAT(name, '%')
  AND capital <> name

2 SELECT from World

2.1 Introduction

SELECT name, continent, population FROM world

2.2 Large Countries

SELECT name FROM world
WHERE population > 200000000

2.3 Per capita GDP

SELECT name, gdp/population
FROM world
WHERE population > 200000000

2.4 South America In millions

SELECT name, population/1000000
FROM world
WHERE continent = 'South America'

2.5 France, Germany, Italy

SELECT name, population FROM world
WHERE name IN ('France','Germany','Italy')

2.6 United

SELECT name FROM world
WHERE name LIKE '%United%'

2.7 Two ways to be big

SELECT name, population, area FROM world
WHERE area > 3000000 OR population > 250000000

2.8 One or the other (but not both)

XOR learning (veterans say they don’t watch)

SELECT name, population, area FROM world
WHERE area > 3000000 XOR population > 250000000

2.9 Rounding

SELECT 
  name,
  ROUND(population/1000000,2),
  ROUND(gdp/1000000000,2)
FROM world
WHERE continent = 'South America'

2.10 Trillion dollar economies

SELECT name, ROUND(gdp/population, -3)
FROM world
WHERE gdp > 1000000000000;

2.11 Name and capital have the same length

SELECT name,
       capital
  FROM world
 WHERE LENGTH(name) = LENGTH(capital)

2.12 Matching name and capital

SELECT name, capital
FROM world
WHERE name <> capital 
  AND LEFT(name, 1) = LEFT(capital, 1)

2.13 All the vowels

SELECT name
   FROM world
WHERE name LIKE '%a%'
  AND name LIKE '%e%'
  AND name LIKE '%i%'
  AND name LIKE '%o%'
  AND name LIKE '%u%'
  AND name NOT LIKE '% %'