Perform Calculations (Cambridge International IGCSE ICT)
Exam board Cambridge International · IGCSEUpdated 2024-06-27
Spec point —
18.2.1
Perform calculations
How do you perform calculations in a database?
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In a database, you can use arithmetic operations or numeric functions to perform calculations
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Calculated fields are fields that carry out a calculation based on other number fields in the database
- For example, a 'products' table with a
stockandunit_pricefields - You could use a calculated field named
stockvalueto calculateunit_price*stock - This calculation multiplies the price of each item by its quantity to find the total value of the stock
- For example, a 'products' table with a
Adding a calculated field to a database table
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Calculated controls are objects you place on forms or reports to display the result of an expression
- For example, a form in a sales database where you input the
QuantitySoldandUnitPrice - A calculated control could be used to display the
TotalSale TotalSale = QuantitySold * UnitPrice- This displays the total sale on the form without storing it in the database
- For example, a form in a sales database where you input the
Using formulae and functions to perform calculations
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Databases allow you to use formulae and functions to perform calculations at run time
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This can include basic arithmetic operations: addition, subtraction, multiplication, and division
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For example, you have a discount field and you want to subtract it from the total cost, you could use a subtraction operation like this:
FinalCost = TotalCost - Discount
Aggregate functions
- You can also use aggregate functions to calculate statistical information about a set of records
- Some examples include:
| Sum | Adds together all the numbers in a column | SUM(TotalCost) |
|---|---|---|
| Average | Computes the average of a set of numbers in a column | AVERAGE(Price) |
| Maximum | Finds the highest number in a column | MAX(Price) |
| Minimum | Finds the lowest number in a column | MIN(Price) |
| Count | Counts the number of rows in a column | COUNT(ProductID) |
- Remember that the actual syntax and function names might differ slightly depending on the specific database system being used.
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