Procedimento com parâmetro IN

1. 
   Você pode criar uma função SQL CLR.
   

   [Microsoft.SqlServer.Server.SqlFunction(Name="fnToList", FillRowMethodName="FillRow", TableDefinition="ID NVARCHAR(1000)")]
   public static IEnumerable SqlArray(SqlString inputString, SqlString delimiter)
   {
       if (string.IsNullOrEmpty(delimiter.Value))
           return new string[1] { inputString.Value };
       return inputString.Value.Split(delimiter.Value.ToCharArray(), StringSplitOptions.RemoveEmptyEntries);
   }
   
   public static void FillRow(object row, out SqlString str)
   {
       str = new SqlString((string)row);
   }
   

CREATE FUNCTION [dbo].[fnArray] ( @Str varchar(8000), @Delim varchar(1) = ' ' )
returns  @tmpTable table ( arrValue varchar(25))
as
begin
   declare @pos integer
   declare @lastpos integer
   declare @arrdata varchar(8000)
   declare @data varchar(25)

   set @arrdata = replace(replace(replace(replace(upper(@Str),@Delim,'|'),'-',''),'/','|'),'\','|')
   set @arrdata = @arrdata + '|'
   set @lastpos = 1
   set @pos = 0
   set @pos = charindex('|', @arrdata)
   while @pos <= len(@arrdata) and @pos <> 0
   begin
      set @data = substring(@arrdata, @lastpos, (@pos - @lastpos))
      if rtrim(ltrim(@data)) > ''
      begin
         if not exists( select top 1 arrValue from @tmpTable where arrValue = @data )
         begin   
            insert into @tmpTable ( arrValue ) values ( @data )
         end
      end
      set @lastpos = @pos + 1
      set @pos = charindex('|', @arrdata, @lastpos)
   end
   return 
end

SELECT * From Mydatabase Where Names in (select arrValue from dbo.fnArray(@Names, ','))