Data Analyst

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

SQL is this role's daily tool, not one line on the job spec. A four-level path from your first SELECT to the schema and performance questions a senior analyst gets asked.

How much SQL this role needs

Core, daily

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

L0Get the interview

0 / 25

Can you write the query at all. The syntax every SQL interview screens for.

1 item here is Basic — see plans

SQL lessonStart here: SQL & this tutorial SQL lessonSELECT: reading data SQL lessonWHERE: filtering rows SQL lessonNULL: the three-valued logic trap SQL lessonAND, OR, NOT: combining conditions SQL lessonIN & BETWEEN: matching sets and ranges SQL lessonLIKE: pattern matching text SQL lessonORDER BY & LIMIT: top-N SQL lessonArithmetic operators & precedence SQL lessonMath functions: ROUND, ABS, CEIL, FLOOR SQL lessonCASE WHEN: conditional logic SQL lessonString functions SQL lessonDate & time functions SQL lessonAggregate functions: SUM, AVG, COUNT, MIN, MAX SQL lessonGROUP BY: one row per group SQL lessonJOINs: combining tables Excel lessonStart here: Excel & this tutorial Excel lessonYour first formula: =, references, and SUM Excel lessonReferences and the $: relative vs absolute SQL questionShipped or delivered orders worth over RM 100 SQL questionClassify insurance policies into tiers SQL questionCheapest flights to a destination SQL questionShow each transaction with its merchant name SQL questionEmployees who out-earn their managerBasic Excel questionApply a fixed cashback rate down a column

L1Don't break things in your first 90 days

0 / 19

The traps that don't show up in a syntax test: NULLs, timezones, silent dedup, a number that doesn't match the dashboard.

2 items here are Basic — see plans

SQL lessonNULL, deeper: COALESCE & NULLIF SQL lessonHAVING: filtering groups, not rows SQL lessonQuery execution order SQL lessonSelf-joins & joining 3+ tables SQL lessonSet operations: UNION, INTERSECT, EXCEPT Excel lessonNested IF and IFS: Excel's CASE WHEN Excel lessonSUMIFS, COUNTIFS, AVERAGEIFS: conditional aggregation Excel lessonText I: LEFT, RIGHT, MID, LEN, FIND, SEARCH Excel lessonDates I: the serial-number model Excel lessonLookups: VLOOKUP, INDEX+MATCH, XLOOKUP Excel lessonError values: IFERROR, IFNA, and knowing which to reach for Excel lessonCleaning: TRIM, PROPER, SUBSTITUTE, VALUE Excel lessonDuplicates and distinct counts: COUNTIF, UNIQUE SQL questionFlag shipments that breached their SLA SQL questionDays remaining until subscription expiry SQL questionUtilisation rate per consultant Excel questionFlag Carousell listings that were posted more than once Excel questionClean a messy status column, then roll it up by branchBasic SQL questionParse quantity and price out of receipt linesBasic

L2Be trusted with a question

0 / 20

Own an analysis end to end — window functions, subqueries, and a real take-home with a written deliverable, not just a query.

11 items here are Basic — see plans

SQL lessonSubqueries & CTEs SQL lessonWindow functions SQL lessonLAG, LEAD & NTILE SQL lessonPivoting: rows into columns SQL lessonWriting clean, maintainable SQL Excel lessonCross-tabs: building a pivot table out of formulas SQL questionFind duplicate fraud alerts on the same cardBasic SQL questionDrivers rated above averageBasic SQL questionShow every top-up next to the overall average SQL questionNumber each subscriber's reloads in order SQL questionRunning total of daily sales SQL questionSecond most expensive product per category SQL questionPrevious month's revenue SQL questionSplit mudarabah profit across depositors by weighted balance SQL questionRank customers by spendBasic SQL questionDay-over-day change in order volumeBasic SQL questionSplit customers into spending quartilesBasic SQL questionTotal spend per customerBasic SQL questionTotal paid, joined across three tablesBasic SQL questionAccounts above their own branch's averageBasic Take-homeYour First Week as an Analyst Take-homeShopee — Cohort RetentionBasic Take-homeAirAsia — Route ProfitabilityBasic Take-homeMaybank — Fraud TriageBasic

L3Senior signals

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Schema design, index and query performance, and reading an experiment result — what separates a senior analyst from someone who just knows more SQL functions.

6 items here are Basic — see plans

DatabaseWhat a table really is DatabasePrimary keys and uniqueness DatabaseForeign keys and referential integrity DatabaseNormalization I: fixing repeating groups DatabaseIndexes Excel lessonDynamic arrays: FILTER, SORT, and spill Excel lessonCapstone: clean it, then roll it up SQL questionAdd a primary key to an unkeyed orders table SQL questionClose the loophole on a column that's never actually null SQL questionEnforce uniqueness the way a UNIQUE constraint actually works 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 SQL questionConversion rate per variant SQL questionNovelty effect over four weeks SQL questionUsers assigned to both variantsBasic SQL questionPooled standard error and z-scoreBasic SQL questionSimpson's paradox in an A/B testBasic SQL questionRequired sample sizeBasic Excel questionTop Electronics sellers by sales, filtered and sorted in one formulaBasic Excel questionBuild a two-way cross-tab of Boost wallet top-upsBasic

What this site doesn't teach for Data Analyst

A BI tool (Tableau, Power BI, Looker) — the query is the same, the chart layer isn't taught here.
Python or R for statistics beyond what plain SQL can express.
Stakeholder management — scoping an ambiguous request, pushing back on a bad metric, presenting to a non-technical audience.
dbt or a modern data-modeling stack — see the site's own dbt notes if you're curious why not yet.

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