Glossary · Data Analytics

What is SQL JOIN?

A SQL operation that combines rows from two tables based on a related column.

In more detail

INNER JOIN keeps only matching rows; LEFT JOIN keeps every row from the left table, with NULLs where there is no match — useful for finding what is missing.

Example

Joining orders to customers on customer_id to get each order’s city.

Learn it properlySQL for Data Analysis: GROUP BY, JOINs and Window Functions13 min lesson · Data Analytics

Related terms

Full glossary

Data CleaningFixing or removing incorrect, duplicate, inconsistent and missing data so analysis can be trusted.DataFrame (pandas)A table of rows and columns in Python’s pandas library, used to clean, analyse and reshape data.KPI (Key Performance Indicator)A number that shows how well a business or team is doing against an important goal.Pivot TableA spreadsheet tool that summarises data — sums, counts, averages — grouped by categories, by dragging fields.Window FunctionA SQL function that calculates across related rows without collapsing them into one row.