How can I perform SQL ORDER BY exposure, focal and iso (in numeric not string)

问题

The columns for Exposure, Focal, and Iso are not being sorted properly. It seems like they are all being interpreted as strings and sorted as such. For example, if I sort Exposure down, the values can look like this:

1/800, 1/800, 1/800, 1/80, 1/675, 1/640, 1/60, 1/500

If I sort the Focal, it can look like this:

1.4, 1.4, 1.4, 14.0, 14.0, 1.3, 13.0, 1.2, 1.2, 12.0, 1.0, 10.0

and if I sort by ISO, it can look like this:

800, 800, 800, 80, 80, 640, 640, 60, 500, 500, 50

EDIT: My other question (and answers) for doing all this in one single sql query.

回答1:

I tested this on Oracle

with 
   w_data AS(
      select '1/800' exposure from dual union all
      select '1/80'  from dual union all
      select '1/675' from dual union all
      select '1/640' from dual union all
      select '1/500' from dual 
   )
select *
  from w_data
 order by 1 / to_number(substr(exposure, 3, length(exposure)))

For focal you do ORDER BY to_number(focal) and the same for ISO.

Note that exposure example will only work if first 2 characters are always '1/'. I can rewrite it for more general case, like '2.9/700', if you wish

来源：https://stackoverflow.com/questions/7605069/how-can-i-perform-sql-order-by-exposure-focal-and-iso-in-numeric-not-string

标签

sql