@startuml
hide footbox
participant "a Handler" as H
participant "a Query\nCommand" as Q
participant "a Database\nStatement" as D

[->H: query database
create Q
H->Q: new
note left: 生成
activate Q
create D
Q->D: new
Q->D: execute
activate D
Q<--D: results
deactivate D
Q->Q: extract results
activate Q
deactivate Q
Q->D: close
destroy D
note right: 他のオブジェクト\nによる削除
deactivate Q
H<--Q: results
note right: 自己削除
destroy Q
@enduml