两个DATE数据类型值之差是它们之间的 * 天 * 数，所以你必须做一些算术来提取天/小时/分钟，或者-另...
DATEDIFF Calculates the difference between two dates in MySQL and SQL Server. DATEPART Extracts a specific part of a date/time value in SQL Server. GETDATE Retrieves database time in SQL Server. SYSDATE Retrieves database time in Oracle and MySQL. EXTRACT Retrieves a certain component ...