Trying to sum transaction amounts into daily bins. Need help

Databases
1

I’m trying to write a query that sums transaction amounts in my transactions table by day (or week, or month) in order to drive a line chart on our front-end.

The relevant table and fields are:

table: transactions
fields: timestamp (datetime)
txn_amount (float)

We’re trying to return two columns in the result. One is the date: “1/1/10” and the other is the sum for that day. I’ve never grouped by time periods before. Thanks!

2 
SELECT DATE_FORMAT(`timestamp`,'%Y-%m-%d') AS thedate
     , SUM(txn_amount) AS total_amt
  FROM transactions
GROUP
    BY thedate