包含字符串的组记录

Question

我有一张包含以下数据的表格:

+----+-----------------+
| id | country         |
+----+-----------------+
|  1 | i'm from usa    |
|  2 | i'm from italy  |
|  3 | i'm from china  |
|  4 | i'm from india  |
|  5 | she's from usa  |
|  6 | he's from china |
+----+-----------------+

我想通过检查country列中的国家/地区名称来了解每个国家/地区的人口.我想要这样的东西:

+---------+------------+
| country | population |
+---------+------------+
| usa     | 2          |
| italy   | 1          |
| china   | 2          |
| india   | 1          |
+---------+------------+

我想我应该使用GROUP BY和COUNT()运作.但是怎么样？谢谢.

Answer 1

如果国家总是在最后,你可以使用它.

select
  case 
    when country like '%usa' then 'usa'
    when country like '%italy' then 'italy'
    when country like '%china' then 'china'
    when country like '%india' then 'india'
  end as ccountry,
  count(*) as population
from Table1
group by ccountry;

如果国家/地区可以在字符串中的任何位置,您可以在此处找到它,假设它位于开头,结尾或中间被包围space.

select
  case 
    when country like '% usa %' then 'usa'
    when country like '% italy %' then 'italy'
    when country like '% china %' then 'china'
    when country like '% india %' then 'india'
  end as ccountry,
  count(*) as population
from 
    (
      select concat(' ', country, ' ') as country
      from Table1
    ) T
group by ccountry