Oracle
天:
Round(to_Number(end_date - start_date))
小时:
Round(to_Number(end_date - start_date) * 24)
分钟:
Round(to_Number(end_date - start_date) * 24 * 60)
秒:
Round(to_Number(end_date - start_date) * 24 * 60 * 60)
毫秒:
Round(to_Number(end_date - start_date) * 24 * 60 * 60 * 60)
MySQL
// 计算两个 DATE,DATETIME 或 TIMESTAMP之间的天数
DATEDIFF(date_expression_1, date_expression_2)