How many payment methods were used to process payments?
select count ( distinct payment_method_code ) from payments
What payment method is used to process payments the most?
select payment_method_code from payments group by payment_method_code order by count ( * ) desc limit 1
And the least used payment method?
select payment_method_code from payments group by payment_method_code order by count ( * ) asc limit 1
How many payment methods has American Express processed?
select payment_method_code, count ( * ) from payments group by payment_method_code having payment_method_code = "American Express"
What about MasterCard?
select payment_method_code, count ( * ) from payments where payment_method_code = "MasterCard"
Can I get the names of all the payment methods used?
select distinct payment_method_code from payments