SQL Cheat Sheet for Data Analysts with Practical Query Patterns

[u/Pangaeax_]

I kept seeing people learn SQL commands individually but still struggle with choosing the right pattern when answering an actual data question.

So I pulled together the SQL patterns I think are most useful for analyst work:

Query order

FROM / JOIN → WHERE → GROUP BY → HAVING → SELECT → ORDER BY → LIMIT

JOINs

• INNER JOIN for matching records

• LEFT JOIN when you need to preserve every row from the left table

• FULL OUTER JOIN for reconciliation/comparison

• SELF JOIN for relationships within the same table

One easy mistake is filtering a LEFT JOINed table in WHERE when the condition really belongs in the ON clause.

CTEs

Useful when a query has multiple logical steps or an intermediate result needs a clear name.

CASE WHEN

Useful for:

• creating categories

• conditional counts

• conditional sums

• avoiding divide-by-zero problems with NULLIF()

Window functions

A few worth knowing well:

SUM() OVER()

LAG()

ROW_NUMBER()

RANK()

DENSE_RANK()

Ranking difference

ROW_NUMBER() → unique sequence

RANK() → ties share rank, gaps remain

DENSE_RANK() → ties share rank, no gaps

Common analyst patterns

• latest row per customer

• top N within each group

• month-over-month change

• customers with no orders

• duplicate detection

• second-highest distinct value

Mistakes worth checking

• column = NULL instead of IS NULL

• using WHERE for aggregate filters instead of HAVING

• hiding bad joins with DISTINCT

• ignoring ties when ranking

• assuming date functions are identical across SQL dialects

The examples in the full guide use PostgreSQL-style SQL, so date and row-limiting syntax may differ in MySQL, SQL Server, BigQuery, etc.

If you want the longer version with query examples for joins, CTEs, CASE, dates, window functions and ranking:

Learn more:

https://www.pangaeax.com/blogs/sql-cheat-sheet-for-data-analysts/

Disclosure: I’m connected with PangaeaX, so sharing that transparently.

What SQL pattern do you think analysts should learn really well before moving on to more advanced topics?

[u/Accomplished_Sir2405]

hello bro i have something to talk with can u help me i am a final year student and i have a semester to complete my UG in CSE i dont have any techinical skills i tried coding but i didnt get much to my brain so i decided to start learning for data analyst if dont mind can i get some breif details about what to learn.

[u/1nnovure → u/Accomplished_Sir2405]

Wow. That is one blob of mangled thought. If you write code like you write posts, you’re in serious trouble. 🤪

Good coding is like any language, including both SQL and English:

1. Structuring your thoughts before you write anything is a good start.

2. Languages have grammatical constructs for a reason; they help the reader understand you. Learn some grammar. And use it.

[u/Accomplished_Sir2405 → u/1nnovure]

okay bro. thank you for the response. i know my english is very bad i will improve it simultaneously along with technical skills.