modify .NET C# function to handle csv value enclosing

I have a .NET C# function which takes data from an sql query and writes them to a CSV file.

However the resulting CSV file is not properly escaped for values which contain quotes (") and comma (,)

We would like to encase those values which contain (,) to quotes and escape the inner quotes if they exist so that the resulting csv is valid.

Here is the function


```
/// <summary>
///
/// </summary>
/// <param name="reader"></param>
/// <param name="filename"></param>
/// <param name="path">if null/empty will use IO.Path.GetTempPath()</param>
/// <param name="extension">will use csv by default</param>
public static void ToCsv(this IDataReader reader, string filename, string path = null, string extension = ".csv")
{
int nextResult = 0;
do
{
var filePath = Path.Combine(string.IsNullOrEmpty(path) ? Path.GetTempPath() : path, string.Format("{0}{1}", filename, extension));
using (StreamWriter writer = new StreamWriter(filePath))
{
writer.WriteLine(string.Join(",", Enumerable.Range(0, reader.FieldCount).Select(reader.GetName).ToList()));
int count = 0;
while (reader.Read())
{
writer.WriteLine(string.Join(",", Enumerable.Range(0, reader.FieldCount).Select(reader.GetValue).ToList()));
if (++count % 100 == 0)
{
writer.Flush();
}
}
}

filename = string.Format("{0}-{1}", filename, ++nextResult);
}
while (reader.NextResult());
}
```

Can you help me fix this?