SQL Logical and Mathmetical Function


Example

SQL has two logical functions – CHOOSE and IIF.

The CHOOSE function returns an item from a list of values, based on its position in the list. This position is specified by the index.

In the syntax, the index parameter specifies the item and is a whole number, or integer. The val_1 … val_n parameter identifies the list of values.

SELECT CHOOSE(2, 'Human Resources', 'Sales', 'Admin', 'Marketing' ) AS Result;
Result
Sales

In this example, you use the CHOOSE function to return the second entry in a list of departments.


The IIF function returns one of two values, based on a particular condition. If the condition is true, it will return true value. Otherwise it will return a false value.

In the syntax, the boolean_expression parameter specifies the Boolean expression. The true_value parameter specifies the value that should be returned if the boolean_expression evaluates to true and the false_value parameter specifies the value that should be returned if the boolean_expression evaluates to false.

SELECT BusinessEntityID, SalesYTD, 
       IIF(SalesYTD > 200000, 'Bonus', 'No Bonus') AS 'Bonus?'
FROM Sales.SalesPerson
GO
BusinessEntityIDSalesYTDBonus?
274559697.5639Bonus
2753763178.1787Bonus
285172524.4512No Bonus

In this example, you use the IIF function to return one of two values. If a sales person's year-to-date sales are above 200,000, this person will be eligible for a bonus. Values below 200,000 mean that employees don't qualify for bonuses.


SQL includes several mathematical functions that you can use to perform calculations on input values and return numeric results.


One example is the SIGN function, which returns a value indicating the sign of an expression. The value of -1 indicates a negative expression, the value of +1 indicates a positive expression, and 0 indicates zero.

SELECT SIGN(-20) AS 'Sign'
Sign
-1

In the example, the input is a negative number, so the Results pane lists the result -1.


Another mathematical function is the POWER function. This function provides the value of an expression raised to a specified power.

In the syntax, the float_expression parameter specifies the expression, and the y parameter specifies the power to which you want to raise the expression.

SELECT POWER(50, 3) AS Result
Result
125000