Description method, is to write exposition with the actual situation of concise language to take things appropriately fully express way, make the sentence more fluent, more smooth, deep expression to explain the meaning.
To the experts' surprise, those who had the greatest improvement spent the most time on non-rem sleep. And other visual or perceptual ability training requires trainees have deep sleep or at the same time with slow wave sleep and rem sleep, in some cases, even closed his eyes one hour also can have very different. Other times, a good night's sleep is necessary.
At present, there is no unified definition of the term data warehouse. The famous data warehouse expert WHInmon gives the following description in his book "building the data warehouse": The data warehouse is a subject oriented ), An integrated, non-volatile, data collection reflecting the time variant used to support management decisions. For the concept of data warehouse we can understand from two levels, first of all, data warehouse is used to support decision-making, analytical data processing, it is different from the existing operating database; Second, the data warehouse is a number of heterogeneous The data sources are effectively integrated, reorganized according to the theme after integration, and contain historical data, and the data stored in the data warehouse are generally no longer modified.