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Intro to SQL Queries
Query relational data
SQL lets you retrieve and combine table data with clear clauses and joins.
- select
- where
- join
- group by
- order by
Select and Filter
Use SELECT columns FROM table WHERE conditions to narrow rows.
Join Data
INNER, LEFT joins link tables on keys; watch for duplicates and nulls.
Aggregate
GROUP BY with COUNT, SUM, AVG summarizes data; ORDER BY sorts results.