SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 3)
   ExpressionList (children 1)
    Asterisk
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      TableIdentifier tab
   Function and (children 1)
    ExpressionList (children 3)
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier a
       Literal \'1\'
     Literal UInt64_0
     Function equals (children 1)
      ExpressionList (children 2)
       Identifier b
       Literal \'a\'