sql 带 ROUND 和除法的查询

Question

Show the name and per-capita GDP for those countries with a GDP of at least one trillion (1000000000000; that is 12 zeros). Round this value to the nearest 1000. Show per-capita GDP for the trillion dollar countries to the nearest $1000.

SELECT name ,
       ROUND(gdp/population,0.01)

from world
where gdp >= 1000000000000

this however produces bugs.

The task can be tested here

Answer 1

The second argument to round is the number of digits after or before the decimal. I would start with:

select name ,
       ROUND(gdp/population, -3)
from world
where gdp >= 1000000000000

A negative number is before the decimal place. You can read the documentation .

Answer 2

用这个

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

Answer 3

You can also try this:

 SELECT NAME, ROUND(GDP/population * 0.001, 0) * 1000 as "PER-CAPITA GDP" 
         FROM WORLD WHERE GDP>= 1000000000000

:) #mysql