How to call scalar function in SQL Server 2008

Call it right: Syntax and naming

When calling scalar functions, it's crucial to follow the correct syntax and ensure accurate function naming.

Use schema: dbo or bust!

Including the schema, typically dbo, before your function name is essential. Skipping this can bring about the dreaded "Invalid object name" error.

/* Don't forget the dbo, or you'll be d'oh-in' at the error message */
SELECT dbo.FunctionName(Parameter) AS Result;
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For function names using special characters or keywords, enter the name surrounded by square brackets:

/* SQL Server loves the square dance of brackets */
SELECT [dbo].[FunctionName](Parameter) AS Result;
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Speak the same language: Parameter matching

Ensure your parameters match the expected data type of your function. Mismatches can result in unexpected outcomes or errors.

/* Order is everything, especially when it's the data type */
SELECT dbo.CalculateTax([Order].TotalPrice) FROM [Order]
WHERE [Order].ID = 1;
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Operation Troubleshoot: Function not working right?

If your function is throwing tantrums, make sure it exists, your spelling and case are correct, and that you have the required permissions.

Common usage scenarios

Scalar functions are real handy-dandy in multiple situations.

Date Manipulation:

Say goodbye to puzzling over date formats or worrying about birthdays.

/* When every day's a holiday, thanks to SQL */
SELECT dbo.ConvertDateToISO(CurrentDate) FROM YourTable;
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Mathematical Operations:

Complex calculations or fiscal forecasts? Sorted.

/* Invest, rest, let SQL do the interest */
SELECT dbo.CalculateCompoundInterest(Principal, Rate, Time) AS Interest FROM Account;
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String Manipulations:

Text changes or analysis, splitting strings, or finding lengths.

/* SQL: parting text strings since forever */
SELECT dbo.ParseEmail(EmailAddress) AS Username FROM Users;
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Custom Business Applications:

Your business rules or computations? Tailored.

/* SQL: Making accounting fun since...Nah, just kidding, but here's your shipping cost */
SELECT dbo.DetermineShippingCosts(OrderID) AS ShippingCost FROM Orders;
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Checking function existence and access

Always verify if you have permission to access the function and that it exists within the database. It's a good idea for avoiding unnecessary bloopers in your SQL scripts.

Dealing with case sensitivity

Beware of those stealthy uppercase and lowercase letters! SQL Server can be a stickler for exact case, depending on the collation. Keep an eye out for those troublemakers in function names and parameters!

Error management

Design your scalar functions to deal with abnormal inputs graciously. Use TRY..CATCH blocks in SQL Server to handle the odd surprises within your functions and their calling SQL context.

Testing for perfection

Keep testing your functions against different inputs to make sure they behave as expected. If your'e using them frequently, optimizing them can help you dodge performance bullet.