It really helps to check your work and see how the changes you make in your SQL code affect the output.
Notice how in each subquery, we lined up the columns from the various modules. In some columns, we pull in different fields but they are each the same data type, and they correspond to the right column title in our resultant “Activities” table.
Then, at least in this case, it is fairly easy to verify that we are pulling in all the correct information. In this example, 17 rows in our Activities table come from the 3 Meetings, 3 Calls, and 11 Tasks.
