I have date stored in varchar in SQL Server as '19-09-2020' and I want to convert it to '2020-09-19'

Question

I have date stored in a varchar column in SQL Server as '19-09-2020'.

I want to convert it to '2020-09-19'.

I have tried this but it's not working:

select convert(varchar, '19-09-2020', 23)

Answer 1

You must specify the source format for convert:

 convert(date, '19-09-2020',105)

This results in a DATE, if you actually want a VarChar again (of course, you shouldn't):

convert(varchar(10), convert(date, '19-09-2020',105), 23)

Answer 2

Do you want string functions?

select concat_ws('-', right(mycol, 4), substring(mycol, 4, 2), left(mycol, 2))
from mytable

On the other hand, if you want to generate a date from that string, then:

select convert(date, mycol, 105) 
from mytable