This technical problem involves writing a SQL query to return all customers who have made a purchase in the last 30 days, as well as the total amount they have spent.
Given a table of transactions, this SQL query will find the total value of all transactions for each day.
This technical problem involves writing a function that takes a string and a character as arguments, and returns the number of times the character appears in the string.
This problem asks for a SQL query that returns the average transaction value for each day. The example input table has three days, with transaction values of 10, 20, and 30 respectively. The expected output table would have the same three days, with average values of 10, 15, and 20.