ZIMSEC O Level · Computer Science · Form 2, Form 3, Form 4
Databases
A database stores organised data so it can be searched and sorted quickly.
- A table holds records (rows) made up of fields (columns).
- Each field has a data type: text, number, date/time, Boolean (yes/no), currency.
- A primary key uniquely identifies each record (e.g. StudentID).
- Queries search for records that meet criteria, e.g. Form = "4" AND Mark > 70.
- Reports present selected data in a printable format; forms make data entry easier.
Spreadsheets
A grid of cells for calculations, identified by column letter and row number (B4).
- Formulas start with =, e.g. =B2*C2.
- Functions: SUM, AVERAGE, MAX, MIN, COUNT, IF.
- Relative references change when copied; absolute references ($B$1) stay fixed.
- Charts show data visually; sorting and filtering organise it.
Worked example: Write a formula in D2 to show "Pass" if the mark in C2 is 50 or more.
=IF(C2>=50,"Pass","Fail")
Uses
School records, stock control, payroll, hospital records, budgets and modelling ("what if" questions).
Exam tip: Use an absolute reference for a single value used in many formulas, like a tax rate or exchange rate.
Check yourself
- What is a primary key?
- Write a formula to find the average of cells B2 to B11.
- Why is $D$1 used instead of D1 in some formulas?
Show answers
- A field that uniquely identifies each record.
- =AVERAGE(B2:B11)
- It is an absolute reference, so it does not change when the formula is copied.
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