Скачать или смотреть How to Pass a String Array to a Stored Procedure in C# and SQL Server

Learn how to successfully pass a `string array` to a stored procedure in SQL Server using C# . Discover different methods and best practices for handling your data.
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How to Pass a String Array to a Stored Procedure in C# and SQL Server

In the world of software development, especially when working with databases, developers often encounter the challenge of passing multiple values to a stored procedure. One common scenario arises when you want to pass a string that contains multiple values (like 123,234,234) to a SQL Server stored procedure that expects a list of values in an IN clause. If you've faced the error "Conversion failed when converting the nvarchar value '123,234,234' to data type int," you're not alone. This post will guide you through understanding the problem and present effective solutions to resolve it.

Understanding the Problem

When you try to use a string containing numeric characters separated by commas in an SQL statement, it does not behave as you might expect. SQL Server does not automatically interpret a comma-separated string as a list of items to check against. As a result, your attempt to do something like the following will lead to an error:

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Why It Doesn't Work

The main takeaway is that the IN clause requires parameters to be passed explicitly, which means you cannot substitute a single string containing multiple comma-separated values directly. Instead, SQL Server expects actual values as parameters, such as:

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In summary, you need to find a different approach to pass multiple values to your stored procedure.

Solutions to Pass String Array to Stored Procedure

1. Passing Individual Parameters

One approach is to pass each value as a separate parameter to the stored procedure. Here’s how you could do it:

Assume you have three values you need to pass: 123, 234, and 345.

Your stored procedure would need to accept three parameters:

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In C# , you would pass the parameters as follows:

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If you are unsure of the number of parameters ahead of time, you can repeat the last value as a placeholder.

2. Using a User-Defined Table Type

For a more dynamic solution, you can create a user-defined table type in SQL Server and pass it to your stored procedure. Here’s how to implement this method:

Step 1: Create a User-Defined Table Type

First, create a table type that will hold your list of integers:

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Step 2: Modify the Stored Procedure

Next, change your stored procedure to accept a parameter of this new type:

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Step 3: Prepare DataTable in C#

In your C# application, you will need to create a DataTable to represent the table type and fill it with the integers:

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Step 4: Pass the DataTable as a Parameter

Finally, you can execute your command while specifying the parameter as structured:

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Conclusion

Passing a string array to a stored procedure in SQL Server from C# is not straightforward, but with the appropriate methods, such as individual parameters or user-defined table types, you can effectively achieve your goal. Instead of relying on implicit string conversions, utilize these techniques to ensure your application communicates seamlessly with your database. By doing so, you avoid common pitfalls and create a more robust and reliable application.

For any developer dealing with SQL Server and C# , understanding how to pass multiple values correctly can save you from confusion and errors down the line. Happy coding!