Creating computed columns and complex expressions
Using SQL, you can manipulate data to return it in the format that you require. You can create computed columns that return values derived from multiple fields, for example:
QuantityOrdered * PriceEach
ContactFirstName || ' ' || ContactLastName
You can aggregate data using SQL functions, for example:
You can create statements that provide if-then-else logic, for example:
CASE WHEN QuantityInStock > 0 THEN 'In Stock' ELSE 'Out of Stock' END
How to create a computed column
In Expression Builder, select the type of expression to build and choose Next. Expression Builder displays different properties depending on the expression type.
Figure 2-6 shows an example of a function expression. The expression uses an aggregate function, SUM, to calculate order totals. The expression, SUM(QUANTITYORDERED * PRICEEACH), is created by selecting the SUM function, and the required columns and operator to use in the calculation.
Figure 2-6  
Choose Finish. The computed column appears under Columns.

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