I use Oracle but below is how I would try it in SQL-Server:

    update tablename
    set fieldname = concat(substring(fieldname, 1, (length(fieldname) - 7)), 'FY16-Q1')
    where fieldname like '%FY15-Q2'

It would probably be helpful to explain what I am doing in the `substring()` function so here it goes:

> Update fieldname to be itself but remove the unwanted 7 chars `FY15-Q2` at the end and instead concat the string with FY16-Q1