SQL 条件聚合
示例
付款表
select customer, sum(case when payment_type = 'credit' then amount else 0 end) as credit, sum(case when payment_type = 'debit' then amount else 0 end) as debit from payments group by customer
结果:
select customer, sum(case when payment_type = 'credit' then 1 else 0 end) as credit_transaction_count, sum(case when payment_type = 'debit' then 1 else 0 end) as debit_transaction_count from payments group by customer
结果: