PostgreSQL: IN A SINGLE SQL SYNTAX order by numeric value computed from a text column

Question

A column has a string values like \"1/200\", \"3.5\" or \"6\". How can I convert this String to numeric value in single SQL query?

My actual SQL is more complicated, h

Answer 1

Seeing your name I cannot but post a simplification of your answer:

SELECT id, number_value_in_string FROM table
 ORDER BY CASE WHEN substr(number_value_in_string,1,2) = '1/'
        THEN 1/substr(number_value_in_string,3)::numeric 
        ELSE number_value_in_string::numeric END, id;

_{Ignoring possible divide by zero.}