OCR Computing Chapter 5
- Created by: AliceSarah
- Created on: 06-06-17 21:28
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- Ch. 5 - Databases
- Uses
- Used everywhere - banks, school
- Make data easy to access, sort, search, copy, protect, group
- Give staff enough info to do their jobs - no more
- Data Matching - finding known patterns, Data Mining - new patterns
- CRUD - create, read, update, delete
- Security & Integrity
- Data lost b/c of fire/flood, accidental/ purposeful deletion
- Integrity maintained by validation - Length Check (password), Type Check (only letters in name), Range Check (DOB), Lookup Check (password must match)
- Protected against loss by - backups, Cloud, restricted access, stored in 2 places
- Security - kept safe. Integrity - true
- Data Models
- Models = database structures
- Heirarchical - used for inventory
- Flat File - most basic, like a spreadsheet. row = record, column = field BUT has data redundancy & inconsistent updates
- Relational uses multiple tables, linked by primary/ foreign keys. Each table has data about 1 entity. Crows foot diagrams - 1 entity, many relationships
- General
- Persistent organised store of data on secondary storage, can be easily processed
- Errors lead to money loss, embarrassment, life/death situations
- Protected against errors, loss, insufficient/inconsistent data, unauthorised access
- Organisations depend on them. Must be accurate, up to date, protected, readily available
- DBMS
- Can create applications, protect data, run queries, keep data consistent & accurate
- Transactions = changes. Must not damage integrity
- Connect apps to data, so -sharing data is easier & only 1 copy - consistent
- Multi User - Record locking if 1 person edits record, it is locked for editing by all others
- Tools to create/modify tables, & link them together
- Choice of data types
- Forms (e.g. buttons) -user friendly interface
- Reports - summarise, group & select data output
- Queries - AND, OR
- Graphs (only some) display data for presentation
- Auto-backup protects safety (only in some)
- Uses
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