How to Use SQL Parameters with an IN Clause and a List of Strings?

Performing an IN Query with a List of Strings using SQL Parameters

Your code attempts to execute an IN statement using a List as the parameter for the @settings SQL parameter. However, this approach is not valid as it requires a supported data type for binding.

To execute an IN query with a list of strings, you can follow these steps:

1. Create a string query template: Construct a string query that includes placeholders for each element in the list. For example:

string sql = "SELECT dscr FROM system_settings WHERE setting IN ({0})";

2. Convert the list to an array of parameters: Create an array of parameter names, where each name corresponds to a placeholder in the query template.

string[] paramArray = settingList.Select((x, i) => "@settings" + i).ToArray();

3. Format the query: Replace the placeholders in the query template with the parameter names.

cmd.CommandText = string.Format(sql, string.Join(",", paramArray));

4. Add the parameters to the command: Create and add a SqlParameter for each element in the list, using the corresponding parameter name and value.

for (int i = 0; i < settingList.Count; ++i)
{
    cmd.Parameters.Add(new SqlParameter("@settings" + i, settingList[i]));
}

By following these steps, you can safely perform an IN query with a list of strings using SqlCommand parameters. This approach involves creating a custom parameter name for each string in the list and specifying the appropriate data type for the SqlParameter.

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