Tracking Changes In SQL Models

Why this matters

As a BI Analyst, your SQL models power dashboards, KPIs, and decisions. When logic changes, stakeholders need to know what changed, why it changed, and how to roll back if needed. Tracking changes gives you:

• Auditability: every SQL change is documented with a reason.
• Safe iteration: test changes on a branch before merging to production.
• Clear reviews: diffs show exactly what lines changed.
• Fast rollback: revert to a previous version if metrics look off.

Who this is for

• BI Analysts and Analytics Engineers creating SQL models for reporting.
• Data-savvy Product/Operations analysts who deliver recurring SQL updates.
• Anyone new to Git who wants to manage SQL safely and clearly.

Prerequisites

• Basic SQL: SELECT, JOIN, GROUP BY, CASE.
• Basic Git: git init, add, commit, status.

Concept explained simply

Think of SQL models as source code. Each meaningful change should be a commit with a short, clear message. You compare versions with a diff, review on a branch, and merge when ready. Structural changes to warehouse tables are tracked with migration scripts (e.g., ALTER TABLE) plus model updates.

Mental model

Picture your SQL models like a Google Docs document with version history. Git is the version history: every change is labeled, comparable, and reversible. Branches are draft copies; main is the approved document.

Core workflow (step-by-step)

1. Create a branch for your change (e.g., feature/add-new-metric).
2. Make a focused change in a .sql file. Format consistently to keep diffs clean.
3. Stage and commit with a clear message describing intent, scope, and why.
4. Run queries/tests locally or in a staging environment.
5. Open a review (pull request) for feedback. Merge when approved.
6. If something breaks, roll back using Git (revert or restore a file to a prior commit).

Worked examples

SELECT
  order_id,
  amount AS revenue
FROM orders
WHERE status = 'paid';

SELECT
  o.order_id,
  o.amount - COALESCE(r.refund_amount, 0) AS revenue
FROM orders o
LEFT JOIN refunds r ON r.order_id = o.order_id
WHERE o.status = 'paid';

feat(revenue): compute net revenue by subtracting refunds

Reason: Align metric with Finance definition; impacts KPI dashboards.

ALTER TABLE orders ADD COLUMN sales_channel VARCHAR(50);

SELECT
  order_id,
  customer_id,
  amount,
  sales_channel
FROM orders;

chore(schema): add sales_channel to orders table
feat(orders_clean): select sales_channel for downstream models

-- migration
CREATE OR REPLACE VIEW monthly_revenue AS SELECT * FROM rev_monthly;

feat(model): create rev_monthly and compatibility view monthly_revenue
refactor(downstream): switch references to rev_monthly
chore(cleanup): drop compatibility view monthly_revenue

Common mistakes and self-check

• Mixing multiple unrelated changes in one commit. Self-check: Can you summarize the change in one sentence? If not, split it.
• Noisy diffs due to reformatting + logic changes together. Self-check: Commit formatting separately.
• Forgetting migration scripts for schema changes. Self-check: Any new/removed/renamed column? If yes, add a migration.
• Vague commit messages. Self-check: Does the message say what changed and why?
• No rollback plan. Self-check: Can you point to the exact commit to revert if KPIs spike?

Exercises

These mirror the tasks in the Exercises section below. You can complete them locally with Git or in any Git-enabled environment.

Exercise 1 — Track a logic change in a SQL model (ex1)

• Create a repo folder and a file models/revenue.sql with a simple revenue query.
• Commit it. Change the logic to net revenue and commit again.
• Use git diff and git log to verify changes and messages.

Exercise 2 — Add a column with migration + update model (ex2)

• Write a migration to add sales_channel to orders.
• Update a model to select the new column.
• Make two separate commits and review diffs.

Practical projects

• Metric evolution tracker: Build a folder with a sequence of commits showing how a KPI definition evolves; document impact notes in commit bodies.
• Schema change cookbook: Create a repo with example migrations (add/rename/drop columns) and corresponding model updates.
• Rollback simulation: Introduce a bug in a branch, merge it, then practice reverting the commit and verifying the fix.

Learning path

• Before this: Git fundamentals, basic SQL modeling.
• Now: Tracking changes in SQL models (this lesson).
• Next: Branching strategies, code review practices, adding tests and data quality checks.

Mini challenge

Your stakeholder requests a new discount logic. Make a branch, implement the logic change in the discounts model, commit with a clear message, and prepare a short note in the commit body describing expected KPI impact and how to validate it. Keep the diff minimal and focused on the logic change.

Next steps

• Adopt a consistent commit style: type(scope): summary + why.
• Practice small, focused commits and clean diffs.
• Introduce lightweight reviews for every model change.

Progress and quick test

Take the quick test to check your understanding. The test is available to everyone. Only logged-in users will have their progress saved automatically.