Time to “English” – Friday Function

I though about starting a new series that I will add to over time the Friday function, I might not be able to create something as useful as Serge Rielau (@srielau) but maybe it will helpful to someone. Over the last few days I have been asked to some interesting things with “my” data like converting times to a more “friendly” format.

The ask

To convert my nicely cleansed times (19:47:45 or 04:23:32) from various non standard sources (the wonders of Big Data) into a time format that is more compatible with your average email reader (7:47pm or 4:23am) as opposed to a techie that might be all right with the nice 24 hour times. I did a lot of searching around and I could not find any inbuilt functions of DB2 LUW that would do this and so I had to create my own user defined function. Please if you know of anything feel free to correct me, but searching the info center then there was nothing.

DB2 Time to “English” – Code

CREATE FUNCTION GLOBAL.CONVERT_TIME_12H(IN_TIME TIME)
DETERMINISTIC
NO EXTERNAL ACTION
RETURNS VARCHAR(10)
LANGUAGE SQL
BEGIN ATOMIC
    ----------------------------------------------------------------------------
    ----------------------------------------------------------------------------
    --Takes 24hrs time in gives back 12hrs time suffixed with AM or PM
    ----------------------------------------------------------------------------
    ----------------------------------------------------------------------------
    DECLARE OUT_TIME VARCHAR(10);

    IF(INT(LEFT(IN_TIME,2)) <= 12) THEN
        SET OUT_TIME = LEFT(IN_TIME,5) || 'am';

        IF(INT(LEFT(IN_TIME,2)) IN (10,11)) THEN
            RETURN REPLACE(OUT_TIME,'.',':');
        ELSE
            RETURN REPLACE(SUBSTR(OUT_TIME,1),'.',':');
        END IF;

    ELSE
        IF(INT(LEFT(IN_TIME,2)) = 24) THEN
            SET OUT_TIME = '00:00am';
        ELSE
            SET OUT_TIME = LEFT((IN_TIME - 12 HOURS),5) || 'pm';
        END IF;

        RETURN REPLACE(OUT_TIME,'.',':');
    END IF;

END

As you can see it takes in standard DB2 time, and I think managed to get all the gotchas like midnight not being 12 hours less. The downside of this function is that the format becomes text and therefore not useable so would not recommend using it for anything but for human format. As I said before if you know of a function to do this in DB2 that is built in I would love to know.

Future articles

In future Friday Functions then I will look at covering non standard asks that I have been required to do. I think after this one I will be needing to create a function to “elongate” a date!