How to Call a Stored Procedure with Multiple Types in C# on .NET Core: Avoiding Common Errors

Discover how to properly call a stored procedure in C- on .NET Core when using custom SQL types. Learn the right syntax to avoid type clash errors.
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Calling a Stored Procedure with Custom Types in C- on .NET Core: A Guide

Working with stored procedures in SQL Server is a common task for developers, especially when integrating with applications built on .NET Core. However, issues can arise when custom types are involved. If you're trying to call a stored procedure that takes multiple custom types as parameters and running into errors, you’re not alone. Let’s break down how to handle this scenario correctly.

The Problem

In a particular case, a stored procedure named SP-Name is created with two specific table types: Type1 and Type2. The procedure accepts these types as parameters along with an integer and a string. When attempting to call this stored procedure in C-, you may encounter an error:

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This error occurs because of a misunderstanding regarding how SQL Server matches passed parameters to defined procedure parameters based on their order.

Understanding the Error

Parameter Mismatch

The crux of the issue stems from the way parameters are passed in SQL when calling stored procedures. Here's what happens:

Parameter Naming vs. Positioning: In your C- code, you may have assumed that the names of the parameters would bind correctly to the stored procedure’s parameters (i.e., -Item1 to -Item1). However, SQL Server binds parameters by their position, not by their names.

Type Clash: Since your code attempted to pass the structured -Item1 parameter, but the first position of the stored procedure parameters expects an int (the -Id parameter), this leads to a type clash.

Solution Approach: To avoid this confusion, you must explicitly define the parameters you want to pass and their corresponding values in your C- code.

How to Correctly Call the Stored Procedure

There are two main approaches to resolve the problem and call the stored procedure effectively:

1. Explicit Parameter Passing

You can call the stored procedure while explicitly defining which parameter you are passing. Here’s how you can do that:

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2. Simplifying the Stored Procedure

If the other parameters (-Id and -UserName) are not being utilized in your logic, a more straightforward approach would be to simplify the stored procedure by removing these unnecessary parameters altogether.

Updated Stored Procedure:

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Then, you can simply execute it with:

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This approach reduces complexity and avoids the potential for errors arising from parameter mismatches.

Conclusion

When dealing with stored procedures in C- on .NET Core, especially those that use custom SQL types, it's crucial to ensure that you're passing parameters correctly. Remember to either explicitly specify the parameters you’re passing or simplify the stored procedure if possible. By understanding how parameter binding works, you can avoid common pitfalls like the "operand type clash" error and enhance the reliability of your database operations.

Feel free to share your experiences with stored procedures in C- or ask any questions in the comments below!