ORDER BY CASE WHEN … ELSE … END in PostgreSQL

Question

I have my ORDER BY clause as following:

...
ORDER BY CASE WHEN boolean_column is true  THEN text_column END ASC,
         CASE WHEN boolean_column is false THEN text_column END DESC

Is it somehow possible to replace the second CASE in an ELSE ? It feels odd to have two conditions instead of a regular if else/when else as you normally would do.

Answer 1

If the type of text_column is numeric. you can try this.

ORDER BY CASE WHEN boolean_column is true THEN text_column 
              ELSE -1 * text_column END ASC

Answer 2

You can use this trick to shorten the logic:

ORDER BY (CASE WHEN boolean_column THEN text_column END) ASC,
         text_column DESC

It is still two order by keys though.

Answer 3

You can do the sorting at first, getting the position of each record, and then choose the sorting direction

WITH rows_with_positions AS (
    SELECT
        boolean_column,
        text_column,
        ROW_NUMBER() OVER (ORDER BY text_column) AS position,
        .. 
    FROM your_table
)
SELECT text_column, ..
FROM rows_with_positions
ORDER BY
    CASE WHEN boolean_column
        THEN position
        ELSE -1 * position
        END
    ASC