1. Mark Dixon Page 1 06 – Expression Builder

2. Mark Dixon Page 2 Session Aims & Objectives Aims –To use expressions to perform more complex calculations in forms Objectives, by end of this week’s sessions, you should be able to: –create an expression that calculates a value using existing table fields

3. Mark Dixon Page 3 What is an Expression… A set of Data and Operators Used to select data in a query –"PT0010" Or "PT0011" Or "PT0012" Used to calculate a value –[Unit Price]*[Quantity]

4. Mark Dixon Page 4 When do we use them… In queries –Select records with multiple values –Select records on a calculated value [Order Date] = Now() Sum([Unit Price]*[Quantity]) >= 100 In Reports or Form –Calculate values that are not stored Order Price = Sum([Unit Price]*[Quantity]) VAT = Order Price*0.175

5. Mark Dixon Page 5 Why use Expressions… Only store values that cannot be calculated from others –Wish to use these values –Use additional values for Reports Group Summary Report Summary Allows more flexibility when asking ‘questions’ –Specify more values in a query –Find range Less than Greater than etc.

6. Mark Dixon Page 6 Expression Builder… Let Access do the hard work Built in Expression Builder –Allow easy selection of values –Combination with operators Simple +, -, *, / More complex Sum, LIKE, And, Or, Not Icon

7. Mark Dixon Page 7 Expression Builder… Expression Basic Operators Objects Fields/Groups Values/Operators

8. Mark Dixon Page 8 Expression Builder… ‘Object’ currently in ‘Objects’ in Database General Function Constant Values Basic Operators (AND, OR, NOT, MOD <=, =) Commonly used Expression (Page N of M, Date/Time)

9. Mark Dixon Page 9 Building Expressions… Select vales from the windows –Use ‘Current Object’ for values on the query/form etc being worked on –When using multiple objects Select type from first window ‘Loaded’ from the expanded list ‘Values’ from other windows

10. Mark Dixon Page 10 Uses for Expressions… Calculate a value in a form –Sum of all the order lines –Sum of an order –VAT –Grand Total Selecting records from a Query –When stock falls below a certain level –All orders placed in the last month

11. Mark Dixon Page 11 An Example… Customer Order Form –Similar to the Order details form from last lecture –Views cost of order as well

12. Mark Dixon Page 12 An Example… Build the Order Details Main and Sub Order Form from lecture 5 –Include the cost information as well Products - Unit Price

13. Mark Dixon Page 13 New Sub Form Query… Main form query same as last weeks lecture

14. Mark Dixon Page 14 New Sub Form… Need to add line price –Extend form (left) –Add new Text Box (Details) and Label (Header)

15. Mark Dixon Page 15 Calculating Totals… Text box is Unbound –Open Properties –Set Name –Select Control Source –Click …

16. Mark Dixon Page 16 Calculating Totals… Expression Builder will launch –Must multiple [Quantity] and [Unit Price] –Select values from the relevant list object –Use buttons for simple operators

17. Mark Dixon Page 17 Calculating Totals… –Expression now displayed in the Control Source of the text box –Also in text of box Need to calculate total for all lines –This value will be stored in the footer –Extend footer and add text box and label –Rename –Set control source to Sum the Total values =Sum([Quantity] [Unit Price])

18. Mark Dixon Page 18 Final Sub Form…

19. Mark Dixon Page 19 Creating Main Form… Use same query as last weeks lecture –Create column form –Move fields –Add header –Insert new sub form –Link

20. Mark Dixon Page 20 Creating Main Form…

21. Mark Dixon Page 21 Main Form Totals… Need to add totals to main form –Sub Total –VAT –Grand Total Add 3 text boxes and labels to footer –Format as desired –Set Names and Captions as needed Sub Total –Already calculated on Sub Form footer VAT –=[SubTotal]* 0.175 Grand Total –=[SubTotal]+ VAT]

22. Mark Dixon Page 22 Main Form Totals… Sub Total Box –Set control Source equal to OrderTotal on sub form

23. Mark Dixon Page 23 Sub Total Expressions…

24. Mark Dixon Page 24 VAT…

25. Mark Dixon Page 25 Grand Total…

26. Mark Dixon Page 26 Final Design…

27. Mark Dixon Page 27 Final Form…

28. Mark Dixon Page 28 Tutorial Exercise: Countries Task 1: Use a form and sub-form to enter data for Countries and Continents Task 2: Create a query that includes calculated fields for population density and population change