Tables, records and keys
Part 1 of 1
Read a record before counting
A database table groups records with a stated meaning. A column records an attribute. A primary key identifies one record; a row count counts records with that meaning.
A spreadsheet is useful for one person’s small analysis. Shared data needs consistent keys, rules and relationships. An identifier should remain stable when a person’s name changes.
Worked example
shops: number of shop records. orders: number of order records. A primary key must identify one row uniquely.
Pause and explain. Explain one limitation of putting shops and all of their orders in a single spreadsheet row.