匹配来自两个不同表的两列的字符串

Question

I have created two tables, lets call them table a and table b.

Table A consists of one column of strings called domainType

Table B consists of one column of strings which are substrings to table A's column (called topLevelDomain)

CREATE TABLE a ( rank int, name text, domainType text )

CREATE TABLE b ( topLevelDomain text, domainDescription text)

table a:

 rank     name      domainType
 1        a          com
 2        b          co jp
 3        c          co cn

table b:

topLevelDomain    domainDescription
com               country1
in                country2
cn                country3
...
jp                country30

I want to list the most popular descriptions(countries) according to the rank of the domainType to show this:

Desired result:

country1 -------> since rank is 1 (in table a)
country30 ------> since rank is 2 (in table a)
country2 --------> since rank is 3 (in table a)

I'm having trouble 'relating' the topLevelDomain column with the domainType column and returning the descriptions with the top rank corresponding to the domainType. I hope this makes sense! please let me know to add anymore information.

Answer 1

You can join the tables with the use of the operator LIKE :

select b.domaindescription
from b left join a
on  concat(' ', a.domaintype, ' ') like concat('% ', b.topleveldomain, ' %')
order by case when a.domaintype is null then 1 else 0 end, a.rank

See the demo .
Results:

| domaindescription |
| ----------------- |
| country1          |
| country30         |
| country3          |
| country2          |