SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 4)
   ExpressionList (children 1)
    Function sum (children 1)
     ExpressionList (children 1)
      Identifier a
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier t
   Function isNotNull (children 1)
    ExpressionList (children 1)
     Identifier a
   Function and (children 1)
    ExpressionList (children 2)
     Function isNotNull (children 1)
      ExpressionList (children 1)
       Identifier b
     Function greater (children 1)
      ExpressionList (children 2)
       Identifier c
       Literal UInt64_0