Job-Ready Software Engineering / 04

Data, SQL, and system thinking

35 minutes · Developers and QA professionals

Follow the data

Understand what the feature must remember

From story to data

Who owns it?
Which company and role?
Current status?
Next action?
Due date?

Model the relationships

Primary key identifies a row
Foreign key connects rows
Constraints protect valid data
One user can have many applications

SQL answers business questions

Filter rows
Join related data
Group and count
Order useful results

Edge cases are product behavior

Missing company
Duplicate application
Unknown status
Time zone boundary
Deleted user
Empty search

Demo: investigate a reporting defect

The dashboard says there are no active applications.

Pause: ask a data question

Write one business question
Write the SQL needed to answer it
Explain what the result means

Your artifact

Small schema diagram
Three useful queries
One documented trade-off

Next step

Make the artifact.

Publish your work, then continue to the next lesson.