Session Ready
Exercise

Inner joins and number of rows returned

All of the merges you have studied to this point are called inner joins. It is necessary to understand that inner joins only return the rows with matching values in both tables. You will explore this further by reviewing the merge shown in the video lesson between the wards and census tables. You will alter the tables and examine how this affects the merge between them. The wards and census tables have been loaded for you.

For this exercise, it is important to know that both tables start with 50 rows, and are reset back to their original values after each Step.

Instructions 1/3
undefined XP
  • 1
    • Merge wards and census on the ward column and save the result to wards_census.
    • 2
      • In the wards table, within the ward column, change the value of '1' to '61'.
    • 3
      • In the census table (not ward), within the ward column, change the value of '1' to None.
      • Print the shape of the wards_census.
    Loading