How to Clean Weird Characters from SQL Server varchar Columns Using C# and SQL CLR?

Removing Unwanted Characters from SQL Server varchar Columns

Data imported from external sources often contains unexpected or non-standard characters that need to be removed from SQL Server varchar columns. This article demonstrates how to address this using both C# and SQL CLR functions.

C# Solution using Regular Expressions

.NET's regular expression engine provides a powerful way to handle this. The following C# code uses Regex.Replace to eliminate non-printable characters:

<code class="language-csharp">Regex.Replace(inputString, @"[^\u0000-\u007F]", string.Empty);</code>

SQL CLR Function for Enhanced Functionality

Since SQL Server lacks native regular expression support, creating a SQL CLR function extends its capabilities. The example below, StackOverflowRegexReplace, performs regular expression replacements:

<code class="language-csharp">public static SqlString Replace(SqlString sqlInput, SqlString sqlPattern, SqlString sqlReplacement)
{
    string input = (sqlInput.IsNull) ? string.Empty : sqlInput.Value;
    string pattern = (sqlPattern.IsNull) ? string.Empty : sqlPattern.Value;
    string replacement = (sqlReplacement.IsNull) ? string.Empty : sqlReplacement.Value;

    return new SqlString(Regex.Replace(input, pattern, replacement));
}</code>

To utilize this function:

1. Compile the code into a StackOverflow.dll assembly.
2. Register the assembly within your SQL Server database using CREATE ASSEMBLY.
3. Create the SQL CLR function using CREATE FUNCTION.
4. Invoke the function with your input string, regular expression pattern, and replacement string.

Example Usage:

<code class="language-sql">SELECT [dbo].[StackOverflowRegexReplace] ('Hello Kitty Essential Accessory Kit', '[^\u0000-\u007F]', '')
-- Result: Hello Kitty Essential Accessory Kit</code>

These methods effectively cleanse non-standard characters from your SQL Server varchar columns, improving data integrity and preventing potential issues.

The above is the detailed content of How to Clean Weird Characters from SQL Server varchar Columns Using C# and SQL CLR?. For more information, please follow other related articles on the PHP Chinese website!