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SQL for this career

Data Analyst

Also listed as: Executive, Data · Reporting Analyst · Business Analyst

Four workplace milestones from an entry screening to owning a decision-ready analysis, with a diagnostic route for skills you already have.

How much SQL this role needs

Core, daily

You will write SQL most days — pulling numbers, answering ad-hoc questions, and building the query behind someone else's dashboard.

Milestone 1

Pass the screen

Build the smallest useful SQL and spreadsheet toolkit, then prove you can turn a plain request into a correct result.

0 / 17

Outcome

Write and explain a filtered, grouped, joined result without relying on copied syntax.

Capstone evidence

Return a small analysis with the correct grain, formula, and a result you can defend.

1 item here is Basic — see plans

Already do this at work? Pass the 3-item diagnostic to test out.

Jump to diagnostic

Essential lessons

The minimum concepts worth learning before the applied work.

SQL lessonSELECT: reading data SQL lessonWHERE: filtering rows SQL lessonAND, OR, NOT: combining conditions SQL lessonNULL: the three-valued logic trap SQL lessonORDER BY & LIMIT: top-N SQL lessonCASE WHEN: conditional logic SQL lessonAggregate functions: SUM, AVG, COUNT, MIN, MAX SQL lessonGROUP BY: one row per group SQL lessonJOINs: combining tables Excel lessonYour first formula: =, references, and SUM Excel lessonReferences and the $: relative vs absolute Analysis lessonYou have a dataset. Now what?

Required practice

Complete these to build the milestone through the guided route.

SQL questionShipped or delivered orders worth over RM 100 SQL questionClassify insurance policies into tiers

Level checkpoint

A short, graded check of the milestone — no new lesson content.

Diagnostic

SQL questionCheapest flights to a destinationTest-out SQL questionEmployees who out-earn their managerTest-outBasic

Capstone

Bring the milestone together in work that resembles the job.

Excel questionApply a fixed cashback rate down a columnTest-out

Milestone 2

Deliver trustworthy numbers

Handle the dirty-data traps behind first-month analyst work: NULLs, duplicates, joins, dates, lookups, and mismatched labels.

0 / 18

Outcome

Inspect unfamiliar data, state its grain, clean known quality issues, and reconcile the number before sharing it.

Capstone evidence

Clean a messy operational dataset and leave a reproducible audit trail from source rows to summary.

8 items here are Basic — see plans

Already do this at work? Pass the 3-item diagnostic to test out.

Jump to diagnostic

Essential lessons

The minimum concepts worth learning before the applied work.

SQL lessonNULL, deeper: COALESCE & NULLIF SQL lessonQuery execution order SQL lessonSelf-joins & joining 3+ tables SQL lessonString functions Excel lessonSUMIFS, COUNTIFS, AVERAGEIFS: conditional aggregation Excel lessonLookups: VLOOKUP, INDEX+MATCH, XLOOKUP Excel lessonCleaning: TRIM, PROPER, SUBSTITUTE, VALUE Excel lessonDuplicates and distinct counts: COUNTIF, UNIQUE Analysis lessonFirst look at a tableBasic Analysis lessonMissing is not zeroBasic Analysis lessonDuplicates, and which one you keepBasic Excel analysisWhen a lookup finds nothingBasic

Required practice

Complete these to build the milestone through the guided route.

SQL questionFlag shipments that breached their SLA Excel questionFlag Carousell listings that were posted more than once Excel questionClean a messy status column, then roll it up by branchBasic

Level checkpoint

A short, graded check of the milestone — no new lesson content.

Diagnostic

SQL questionParse quantity and price out of receipt linesTest-outBasic SQL questionTotal paid, joined across three tablesTest-outBasic

Capstone

Bring the milestone together in work that resembles the job.

Data LabClean itTest-outBasic

Milestone 3

Own the analysis

Move from answering a query to framing, checking, and communicating an analysis that another person can act on.

0 / 15

Outcome

Choose the right grain and method, use advanced SQL safely, and turn the result into a recommendation with caveats.

Capstone evidence

Complete an end-to-end take-home: query, validate, explain assumptions, and recommend an action.

6 items here are Basic — see plans

Already do this at work? Pass the 3-item diagnostic to test out.

Jump to diagnostic

Essential lessons

The minimum concepts worth learning before the applied work.

SQL lessonSubqueries & CTEs SQL lessonWindow functions SQL lessonLAG, LEAD & NTILE SQL lessonWriting clean, maintainable SQL Excel lessonCross-tabs: building a pivot table out of formulas Advanced analysisPick the grain before you queryBasic Advanced analysisThe check you run before you trust a tableBasic Advanced analysisOne row per entityBasic Advanced analysisCohorts and retention curvesBasic

Required practice

Complete these to build the milestone through the guided route.

SQL questionFind duplicate fraud alerts on the same cardBasic SQL questionRunning total of daily sales SQL questionPrevious month's revenue

Level checkpoint

A short, graded check of the milestone — no new lesson content.

Diagnostic

SQL questionSecond most expensive product per categoryTest-out SQL questionAccounts above their own branch's averageTest-outBasic

Capstone

Bring the milestone together in work that resembles the job.

Take-homeYour First Week as an AnalystTest-out

Milestone 4

Influence the decision

Develop senior signals: reason about schemas and performance, challenge experiment readouts, and communicate what the evidence cannot prove.

0 / 15

Outcome

Review an analysis as a senior would: test the data model, performance, experiment design, and decision risk.

Capstone evidence

Diagnose a slow analytical workflow and deliver a recommendation that separates evidence, assumptions, and next checks.

8 items here are Basic — see plans

Already do this at work? Pass the 3-item diagnostic to test out.

Jump to diagnostic

Essential lessons

The minimum concepts worth learning before the applied work.

DatabasePrimary keys and uniqueness DatabaseForeign keys and referential integrity DatabaseIndexes Advanced analysisReading an experiment readoutBasic Advanced analysisWas the split even?Basic Advanced analysisDistributions before meansBasic Advanced analysisSignificance without a stats libraryBasic Excel lessonCapstone: clean it, then roll it up

Required practice

Complete these to build the milestone through the guided route.

SQL questionIndex a foreign key column Postgres never indexed for you SQL questionGet the column order right on a composite index SQL questionAbsolute difference and relative lift

Level checkpoint

A short, graded check of the milestone — no new lesson content.

Diagnostic

SQL questionSimpson's paradox in an A/B testTest-outBasic SQL questionRequired sample sizeTest-outBasic

Capstone

Bring the milestone together in work that resembles the job.

Data LabWhy your query is slowTest-outBasic Take-homeAirAsia — Route ProfitabilityBasic

What this site doesn't teach for Data Analyst

A BI tool (Tableau, Power BI, Looker) — the query is the same, but the chart layer is not taught here.
Python or R for statistics beyond what plain SQL can express.
The human side of stakeholder management: negotiating scope, presenting live, and navigating an organisation.
dbt or a modern data-modeling stack — this path focuses on the analysis skills underneath those tools.

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