SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Function count (children 1)
     ExpressionList
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
   Function or (children 1)
    ExpressionList (children 2)
     Identifier col
     Function isNull (children 1)
      ExpressionList (children 1)
       Identifier col
