In the following table, I need to find out the login date and how long a user's session spanned. For example, empid=1 logged in (typeid=1) on 1/1/2009 @ 3:20 and logged off (typeid=2) the same day at 3:25. The output should be:In the following table, I need to find out the
阅读背景：
按一列和两行分组
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