SQL query for finding the longest name and shortest name in a table

Question

I have a table with one of the columns is of type varchar(city). and want to find the longest and shortest of values stored in that column.

select a.city, a.city         


        

Answer 1

You query requires just a few tweaks. The fundamental problem is that you cannot use a in the subquery as you are doing:

select a.city, a.city_length
from (select city, char_length(city) city_length 
      from station 
     ) a
where a.city_length = (select min(char_length(city)) from station) or
      a.city_length = (select max(char_length(city)) from station);

That said, a simpler way to write the query is:

select s.*
from station s cross join
     (select min(char_length(city)) as mincl, max(char_length(city)) as maxcl
      from station
     ) ss
where char_length(s.city) in (mincl, maxcl);