OCR H446 · Component 01 · Computer systems
1.3.2 Databases
SQL, databases, data capture, APIs and exchange formats, relational databases, keys, referential integrity, indexing, ERDs, record locking, ACID, and normalisation.
What to revise
Practise databases.
Start with these questions from the databases topic pack. In the workspace, explain each idea from memory, compare your reasoning with the feedback, then revisit the concepts that need practice.
Use the pack alongside your OCR H446 computer systems revision. Your self-reported confidence helps plan the next review; it is not an exam mark or predicted grade.
- Write SQL to add ItemID 27, ItemName 'Compass' and Price 8.50 to Item(ItemID, ItemName, Price).Write
- Write SQL to select ItemName from Item where Price exceeds the mean Price of all items.Write
- Loan(MemberID,ItemID,MemberName,ItemName) has composite key (MemberID,ItemID). Names depend only on their respective IDs. Explain the 2NF defect and give a decomposition.Apply
- A transfer subtracts money from one balance and adds it to another. Explain atomicity and durability.Apply
- What is a database?Basics
- What are tables, records, and fields?Basics
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