Reformat dates in column

Question

I have some data in an SQLite DB of the form:

id  column1  date
111 280 1/1/2014
114 275 1/2/2014

The date field is of type TEXT. I\'ve been ma

Answer 1

Your current date format has four possible forms:

m/d/yyyy
m/dd/yyyy
mm/d/yyyy
mm/dd/yyyy

To rearrange the fields, extract them with substr() and then combine them again.

It might be possible to determine the positions of the slashes with instr(), but for a one-off conversion, just using four queries is simpler:

UPDATE MyTable
SET date = substr(date, 6, 4) || '-' ||
           substr(date, 1, 2) || '-' || '0' ||
           substr(date, 4, 1)
WHERE date LIKE '__/_/____';

-- this is mm/d/yyyy; similarly for the other forms, modify positions and zeros