Creating Calculated Fields in Access

Overview

This lecture covers how to create and use calculated fields in Microsoft Access queries, including a step-by-step process and best practices.

Calculated fields display values derived from existing data in your query results.
Do not store data in tables that can be calculated; calculate it in queries instead.

Step 1: In an unused column's "Field" row in query design, enter an equals sign (=).
Step 2: Enter your calculation formula using field names exactly as spelled in the database.
Field names with spaces must be enclosed in square brackets (e.g., [Number of Payments]).
You can use mathematical operations and numbers in your formula (e.g., =[Paid]/[NumPayments], or calculate VAT as [Paid]*0.15).
Step 3: Press enter; Access will add a default label (like Expr1:) and the formula.
Replace the default label (Expr1) with a descriptive field name (e.g., Average Payment:).

You can right-click the calculated field column to change its format (e.g., currency).
If you misspell a field name, Access will prompt you to enter a value, indicating an error.
Always double-check field names for accuracy to avoid calculation errors.

To calculate average payment: enter =[Paid]/[NumPayments] and label it Average Payment.
To calculate VAT: enter =[Paid]*0.15 and label it VAT Amount.
Change format to currency for monetary values.

Calculated Field — A column in a query showing values calculated from existing data.
Field Row — The top row in query design where you define fields to display or calculate.
Label — The name shown at the top of the calculated field column.
Square Brackets — Used around field names with spaces in formulas.

Practice creating calculated fields in Access queries using the three-step process.
Double-check formulas for correct field name spelling and formatting.
Watch the next video for advanced calculations involving dates and text.