🔑Define a starting point by selecting a portion of customers to work with
🧩Build data sets from left to right, adding properties of objects one by one
🔗Use left joins to preserve all objects from the starting point
📊Aggregate before joins to avoid duplicates and maintain data set integrity
🗂️Break the logic into steps and solve complex problems one step at a time
What is a data set?
—A data set is a collection of objects and properties associated with these objects. In SQL, data sets are typically represented as tables.
How do you define a starting point for building a data set?
—To define a starting point, you need to select a portion of customers or objects from your database that you want to work with and build a data set for.
Why is it important to use left joins when building data sets?
—Left joins preserve all objects from the starting point, ensuring that no data is lost. This is important for maintaining the integrity of the data set.
What is the benefit of aggregating before joins?
—Aggregating before joins helps avoid duplicates in the resulting data set and ensures accurate calculations of metrics or features.
Why is it recommended to break the logic into steps when building data sets?
—Breaking the logic into steps makes complex problems more manageable and helps maintain clarity and organization in the code or query.
00:00A data set is a collection of objects and properties associated with these objects. In SQL, data sets are typically represented as tables.
03:05To build a data set, you need to define a starting point by selecting a portion of customers or objects from your database that you want to work with.
08:45When building data sets, it is important to use left joins to preserve all objects from the starting point and maintain the integrity of the data set.
11:45Aggregating before joins helps avoid duplicates in the resulting data set and ensures accurate calculations of metrics or features.
18:45Breaking the logic into steps when building data sets makes complex problems more manageable and helps maintain clarity and organization in the code or query.
