Computer science · University
Joins and relationships · revision notes
An operation combining rows according to a relationship condition.
Key ideas and conditions
Join
An operation combining rows according to a relationship condition.
One-to-many
A relationship where one row can correspond to several rows in another table.
Inner join
A join returning rows with matches under the join condition.
Left join
A join retaining all rows from the left side plus matching right-side rows.
Explain without looking
- Give a short example showing how Inner join would be used in practice.
- Summarize why Left join matters in the lesson “Joins and relationships”.
Further reading and review references
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