Your path · can start

Rung 1
Where SQL enters the testing cycle~0.7 h · Orientation
Rung 2 · the author places it after “Where SQL enters the testing cycle”inside a rung the order is up to you
Reading a schema you did not design~0.8 h · Orientation
Staying safe on a shared test environment~0.8 h · Orientation
Optional: client data, PII and AI assistants~0.7 h · Optional
Rung 3
A SELECT that answers exactly one question~0.7 h · Precise retrieval · the author places it after “Reading a schema you did not design”
Rung 4 · Precise retrieval
NULL and the logic that has three answers~0.9 h · the author places it after “A SELECT that answers exactly one question”
Types, conversions and collation~0.8 h · the author places it after any one of these: “Reading a schema you did not design”, “A SELECT that answers exactly one question”
Rung 5
Dates, times and the last day of the month~0.9 h · Precise retrieval · the author places it after any one of these: “A SELECT that answers exactly one question”, “Types, conversions and collation”
INNER and LEFT: which rows the join throws away~0.8 h · Across tables · the author places it after any one of these: “A SELECT that answers exactly one question”, “NULL and the logic that has three answers”
Rung 6
Orphans and links that point at nothing~0.8 h · Across tables · the author places it after “INNER and LEFT: which rows the join throws away”
When a join multiplies your rows~0.9 h · Across tables · the author places it after “INNER and LEFT: which rows the join throws away”
Set operations as reconciliation~0.8 h · Across tables · the author places it after any one of these: “NULL and the logic that has three answers”, “INNER and LEFT: which rows the join throws away”
Optional: slow queries and blocked environments~0.8 h · Optional · the author places it after any one of these: “Staying safe on a shared test environment”, “Dates, times and the last day of the month”
Rung 7
GROUP BY and recomputing the report~0.8 h · Aggregation · the author places it after any one of these: “A SELECT that answers exactly one question”, “When a join multiplies your rows”
Test data: setup and idempotent teardown~0.9 h · Data before and after the test · the author places it after any one of these: “Staying safe on a shared test environment”, “Set operations as reconciliation”
Rung 8
HAVING and finding duplicates~0.8 h · Aggregation · the author places it after “GROUP BY and recomputing the report”
Subqueries and CTEs~0.8 h · Aggregation · the author places it after any one of these: “When a join multiplies your rows”, “GROUP BY and recomputing the report”
Optional: why the schema looks like that~0.7 h · Optional · the author places it after any one of these: “Reading a schema you did not design”, “GROUP BY and recomputing the report”
Rung 9
Window functions for the tester~0.9 h · Aggregation · the author places it after any one of these: “HAVING and finding duplicates”, “Subqueries and CTEs”
Optional: end-to-end migration reconciliation~1 h · Optional · the author places it after 2 of these: “Orphans and links that point at nothing”, “Set operations as reconciliation”, “HAVING and finding duplicates”
Rung 10
Verifying what the application actually wrote~0.9 h · Data before and after the test · the author places it after any one of these: “Window functions for the tester”, “Test data: setup and idempotent teardown”
Rung 11 · Data before and after the test · the author places it after any one of these: “Test data: setup and idempotent teardown”, “Verifying what the application actually wrote”
Reading views, procedures and triggers~0.8 h
Turning a check into a deterministic assertion~0.9 h
Rung 12
Optional: build ENGAGE locally and run the checks~1.5 h · Optional · the author places it after any one of these: “Reading a schema you did not design”, “Turning a check into a deterministic assertion”
Examclosed · in the browser, without the assistant

0 of 24 units done · ~15.7 h without the optional units, ~20.4 h with them

Verifying what the application actually wrote

This unit is open to those enrolled

Enrolment is free — it is what lets the server remember your progress between sessions.