02/12/2025
18 SQL Commands every Data Pro needs to master. 🚀
SQL is the bread and butter of data analysis. Whether you are building pipelines or generating insights, these are the building blocks of your queries.
I've compiled the ultimate quick-reference guide:
👇 The Essentials
🔹 SELECT: The starting point. Retrieves your data.
🔹 WHERE: Your gatekeeper. Filters data based on specific conditions.
🔹 DISTINCT: The cleaner. Returns only unique values.
🔹 ORDER BY: The organizer. Sorts results ascending or descending.
📊 Aggregation & Grouping
🔹 GROUP BY: Groups rows with the same values into summary rows.
🔹 HAVING: Like WHERE, but specifically for filtering GROUP BY results.
🔹 ROLLUP: The summarizer. Generates subtotals and grand totals.
🧮 Math Functions
🔹 COUNT(): Returns the number of rows.
🔹 SUM(): Calculates the total.
🔹 AVG(): Finds the average.
🔗 Combining Data
🔹 JOIN: Merges rows from two+ tables based on a relationship.
🔹 UNION: Stacks result sets from multiple SELECT statements.
🧠 Advanced Logic
🔹 CASE: Adds IF-THEN logic directly into your query.
🔹 CTE: Common Table Expressions. Makes complex queries readable.
🔹 Window Functions: (e.g., RANK) Performs calculations across related rows without collapsing them.
🔹 EXISTS: Checks if a subquery returns any rows (True/False).
⚙️ Performance & Structure
🔹 INDEX: The speed booster for retrieval (at the cost of write speed).
🔹 TRIGGER: Automates actions when specific events happen.
💡 Pro Tip: Don't just memorize the syntax; understand the order of ex*****on. Knowing that WHERE happens before GROUP BY changes everything.
Which one of these do you use the most daily? Let me know in the comments! 👇
