public SqlTableBase AddQuerySource (IQuerySource source, Expression fromExpression)
{
ArgumentUtility.CheckNotNull ("source", source);
ArgumentUtility.CheckNotNull ("fromExpression", fromExpression);
var fromExpressionInfo = _stage.PrepareFromExpression (fromExpression, _context, info => new SqlTable (info, JoinSemantics.Inner));
AddPreparedFromExpression (fromExpressionInfo);
_context.AddExpressionMapping (new QuerySourceReferenceExpression (source), fromExpressionInfo.ItemSelector);
return fromExpressionInfo.SqlTable;
}