Computer Science › Section J · Database systems › Topic J.3
Querying with SQL
SQL is the language almost every relational database understands. A few short, readable statements can filter, combine and summarise tables of any size.
In this topic
- What SQL is
- A small library database
- SELECT, FROM and WHERE
- Sorting, duplicates and limits
- Joining tables
- Worked example: the long loans
- Aggregates and grouping
- Worked example: loans per genre
- Outer joins and NULL
- Changing data and defining tables
- Common mistakes to avoid
- Key takeaways
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