COleTime 与 DATE 数据类型的理解

• COleTime的存在是因为：

It provides finer granularity(更细的颗粒度) and a greater range than
the CTime class.

　　

• 之所能做到上述是因为：

the DATE date type, and also the COleDateTime class, represent
dates and times as a classic number line.

　　

• 这里提到了DATE类型：

The DATE type is implemented using an 8-byte floating-point number.
Days are represented by whole number increments starting with 30
December 1899。

　　

• 有很多种方法来构造一个COleTime对象，用DATE数据类型只是其中一种：

COleDateTime( DATE dtSrc ) 
throw( );