Question

i have come across a mysql database which has dates entered in a varchar column in various random formats e.g below

01/01/1977
05-05-1980
58   ( age to be converted to date )
1.2.1990
02/02/87
01-Mar-73

How do i convert this into one unified format – dd/mm/yyyy

Also when i try to convert varchar into date column with this data

SELECT
    CAST(date_column AS DATE)
    FROM
    table_name 

i don’t know why is it giving me all nulls for date value as a result

Answer 1

I would use regex to check for the format, then use the appropriate specifiers in STR_TO_DATE to get a standard format. Perhaps someone can help on the regex?

Pseudo-code:

SELECT 
     CASE WHEN date REGEXP '[m-d-y]'
          THEN STR_TO_DATE(date, %)

Specifiers: http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date-format