How to Safely Use SQL's IN Statement with SqlParameter and a List?

SQL IN Statement with SqlParameter and List

When attempting to execute an IN statement with a SqlParameter using a List, an ArgumentException can arise due to the inability to map the list to a known provider type. This issue can be resolved by employing the following approach:

1. Convert the List to an Array:
   Convert the List to an array of strings, such as:

   string[] paramArray = settingList.ToArray();

2. Format the SQL Statement:
   Format the SQL statement with a placeholder for each parameter, using the number of parameters in the array:

   string sql = "SELECT dscr FROM system_settings WHERE setting IN ({0})";
   sql = string.Format(sql, string.Join(",", paramArray.Select((x, i) => "@settings" + i)));

3. Add Parameters:
   For each element in the array, add a SqlParameter to the command object, using the appropriate name and value:

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

4. Execute the Command:
   Execute the command as usual:

   reader = cmd.ExecuteReader();

This approach provides a safe and efficient way to execute an IN statement with a List using SQLParameters.

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