SelectWithUnionQuery (children 1)
 ExpressionList (children 1)
  SelectQuery (children 2)
   ExpressionList (children 3)
    Identifier UserID
    Function equals (children 1)
     ExpressionList (children 2)
      Identifier UserID
      Literal UInt64_0
    Function if (children 1)
     ExpressionList (children 3)
      Function equals (children 1)
       ExpressionList (children 2)
        Identifier UserID
        Literal UInt64_0
      Literal \'delete\'
      Literal \'leave\'
   TablesInSelectQuery (children 1)
    TablesInSelectQueryElement (children 1)
     TableExpression (children 1)
      Function VALUES (children 1)
       ExpressionList (children 4)
        Literal \'UserID Nullable(UInt8)\'
        Literal UInt64_2
        Literal UInt64_0
        Literal NULL