CreateQuery test (children 3)
 Identifier test
 Columns definition (children 2)
  ExpressionList (children 2)
   ColumnDeclaration user_id (children 1)
    DataType UInt64
   ColumnDeclaration item_id (children 1)
    DataType UInt64
  ExpressionList (children 1)
   Projection (children 1)
    ProjectionSelectQuery (children 3)
     ExpressionList (children 1)
      Function toString (alias user) (children 1)
       ExpressionList (children 1)
        Identifier user_id
     ExpressionList (children 1)
      Identifier user
     Identifier user_id
 Storage definition (children 2)
  Function MergeTree
  Function tuple (children 1)
   ExpressionList
