InsideEdgeInsideEdge
Download App

Phase 3 · SQL for Data Analysis

Topics

Query Optimization Basics

Part of the Data Analyst Roadmap.

Summary

Understanding why some queries run slowly (missing indexes, unnecessary joins, SELECT *) well enough to write reasonably efficient queries against large tables.

How to Learn This

  • 1Learn what an index is and why it speeds up filtering on a column.
  • 2Practice replacing SELECT * with only the columns you actually need.
  • 3Use EXPLAIN (or your database's equivalent) to see how a query is being executed.

Previous

Date & String Functions

Next

Database Design Basics (ER Diagrams)

More topics in SQL for Data Analysis

SQL Basics (SELECT, WHERE, ORDER BY)Aggregate Functions (COUNT, SUM, AVG)GROUP BY & HAVINGJoins (INNER, LEFT, RIGHT, FULL)SubqueriesCommon Table Expressions (CTEs)Window FunctionsDate & String FunctionsDatabase Design Basics (ER Diagrams)
InsideEdge

Stuck on this topic? Ask an Insider

Get 1:1 guidance from people who've walked this exact path — free on the InsideEdge app.

Download
InsideEdge