Problem

Given a table of transactions, write a SQL query to find the total value of all transactions that occurred on each day.
Input:
transactions table:
+----+------------+----------+---------+
| id | date       | user_id  | value   |
+----+------------+----------+---------+
| 1  | 2020-01-01 | 1        | 100.00  |
| 2  | 2020-01-01 | 2        | 50.00   |
| 3  | 2020-01-02 | 1        | 75.00   |
| 4  | 2020-01-02 | 3        | 25.00   |
+----+------------+----------+---------+
Output:
+------------+-------------+
| date       | total_value |
+------------+-------------+
| 2020-01-01 | 150.00      |
| 2020-01-02 | 100.00      |
+------------+-------------+

Solution

SELECT date, SUM(value) AS total_value
FROM transactions
GROUP BY date;