mysql : turn fraction strings into number

Question

I have strings like... \"3/4\" and \"5/9\" and some like... \"1/2 km\" and \"3/4 degree\" stored in mysql columns.

I would like to convert them into numbers. In first c

Answer 1

The above didn't quite work for me so came up with this which does. The query works for '10', '3/4' and '10 3/4'. Obviously you should replace the constructed rows at the bottom with your string or a selected value from a table:

SELECT 
    IF (
        LOCATE(' ',fraction) > 0 OR LOCATE('/',fraction) = 0,
        SUBSTRING_INDEX(SUBSTRING_INDEX(fraction,'/','1'),' ','1')
        ,0
    ) AS `integer`,
    IF (
        LOCATE('/',fraction) > 0,
        SUBSTRING_INDEX(SUBSTRING_INDEX(fraction,'/','1'),' ','-1'),
        0
    ) AS numerator,
    SUBSTRING_INDEX(fraction,'/','-1') AS denominator,
    (SELECT `integer`) + ((SELECT numerator) / (SELECT denominator)) AS `decimal`
FROM (
    SELECT '10 3/4' AS fraction
    UNION SELECT '10'
    UNION SELECT '3/4'
) t;