Sql Excel : Subscription Dataset

The subscription data has only two entities, shown in Figure 1.2. This dataset
paints a picture of a subscriber at a given point in time (the date when the
snapshot was created).
The Subscribers table describes customers in a telephone company. It is a
snapshot that shows what customers (and former customers) look like as of a
particular date. The columns in this table describe customers as they start and as
they stop. This particular snapshot table has no intermediate behavior
information.
The Calendar table is a general-purpose table that has information about dates,
including:
Year
Month number
Month name
Day of month
Day of week
Day of year
Holiday information
This table has the date as a primary key, and covers dates from 1950 through
2050.