SQL: ORDER BY using a substring within a specific column… possible?

Question

I have a database whose columns are npID, title, URL, and issue.

Here is an example of two years\' entries:

npID               title               UR         


        

Answer 1

You could make the sub string part of the data being selected

SELECT npId, title, URL, issue, SUBSTRING(issue, 4) AS strsort FROM tbl ORDER BY strsort, issue

Answer 2

Try this approach (this is in T-SQL):

select
        *
    from
        your_table as t
    order by
        substring([issue], 1, 4) desc,
        case substring([issue], 6, len([issue]) - 5)
            when 'First_Quarter' then 1
            when 'Second_Quarter' then 2
            when 'Third_Quarter' then 3
            when 'Fourth_quarter' then 4
            when 'Spring' then 3
            when 'Summer' then 2
            when 'Fall' then 4
            when 'Winter' then 1
            else 5 -- show unexpected input last
        end asc

Answer 3

SELECT Column1, row_number() over(order by substring(column2,280,9)) 
FROM YourTable 

This will give the order by of substring column2.

Answer 4

You can put a CASE statement in the ORDER BY to accomplish this. A better route would be to change the application and table to actually store this relevant data in columns where it belongs when you have the development time to do that.

ORDER BY
    CAST(SUBSTRING(issue, 1, 4) AS INT) DESC,  -- Year
    CASE
        WHEN issue LIKE '%First_Quarter' OR issue LIKE '%Winter' THEN 1
        WHEN issue LIKE '%Second_Quarter' OR issue LIKE '%Spring' THEN 2
        WHEN issue LIKE '%Third_Quarter' OR issue LIKE '%Summer' THEN 3
        WHEN issue LIKE '%Fourth_Quarter' OR issue LIKE '%Fall' THEN 4
    END

Order the seasons however you want. You could also order them in a specific way (Q1 followed by Spring, followed by Q2, etc.) by adjusting the CASE statement.

Answer 5

Here's a variation of the same theme

ORDER BY
    SUBSTRING(issue,1,4) Desc,

CASE SUBSTRING(issue,6, LEN(issue) - 5)
   WHEN 'First_Quarter' THEN 1
   WHEN 'Second_Quarter' THEN 2
   WHEN 'Second_Quarter' THEN 3
   WHEN 'Winter' then 1
   WHEN 'Spring' then 2
   WHEN 'Summer' then 3
   WHEN 'Fall' then 4
END

Answer 6

Standard SQL

Try a CASE statement in the ORDER BY:

SELECT npID, title, URL, issue
FROM   tbl
ORDER  BY substring(issue, 1, 4) DESC
      ,CASE 
          WHEN substring(issue, 6, 100) IN ('Winter','First_Quarter')  THEN 1
          WHEN substring(issue, 6, 100) IN ('Summer','Second_Quarter') THEN 2
          WHEN substring(issue, 6, 100) IN ('Spring','Third_Quarter')  THEN 3
          WHEN substring(issue, 6, 100) IN ('Fall',  'Fourth Quarter') THEN 4
          ELSE 5 
       END;

Don't ask, why Winter -> Summer -> Spring - it's what the client wants! :)

Optimize performance

A "simple" CASE should perform better since the expression is only evaluated once.
And right(issue, -5) is equivalent to substring(issue, 6, 100), but a bit faster:

SELECT npid, title, url, issue
FROM   tbl
ORDER  BY left(issue, 4) DESC
      ,CASE right(issue, -5)
          WHEN 'Winter'         THEN 1
          WHEN 'First_Quarter'  THEN 1
          WHEN 'Summer'         THEN 2
          WHEN 'Second_Quarter' THEN 2
          WHEN 'Spring'         THEN 3
          WHEN 'Third_Quarter'  THEN 3
          WHEN 'Fall'           THEN 4
          WHEN 'Fourth Quarter' THEN 4
          ELSE 5 
       END;

left() and right() have been added with PostgreSQL 9.1. The trick with right() is to use a negative number to trim a constant number of characters from the left.

Syntax variants

These are equivalent (for strings of <= 100 characters):

SELECT substring(issue from 6 for 100) AS substring1
      ,substring(issue, 6, 100)        AS substring2
      ,substring(issue, 6)             AS substring3
      ,substr(issue, 6, 100)           AS substr1
      ,substr(issue, 6)                AS substr2
      ,right(issue, -5)                AS right0
FROM tbl

-> sqlfiddle