Question

I am trying to update just the day component on a datetime field on my sqlite database using:

UPDATE recur SET start_date = date('%d', '05')

I have read the documentation but cannot seem to figure out how to do this, can anyone help?

Answer 1

There are good examples in the online documentation. You’re not calling the date function correctly. You need something like:

select date('now', 'start of month', '+4 days');

I’m not sure what date you need to start from, so I used 'now', but you could pass in a date field (from your database, for example) or a valid date string (like “2012-12-05”, at least on my system).

Edit

For example

select date('2012-12-08', 'start of month', '+4 days');

Will return:

2012-12-05

Keep in mind that sometimes when you’re starting with a string it’s easier to use string functions to do this type of manipulation. However using the date function will validate you are starting with a well formatted date.

Edit 2

If you’re also having trouble figuring out the UPDATE syntax, putting it all together you get:

UPDATE recur SET start_date = date(d, 'start of month', '+4 days')
WHERE d = date('2012-12-08');

I’m not sure what exactly you need for the WHERE clause so be sure your selecting the correct records before you run this.