count a occurence of given attribute

hi, i have a two tables named “agents” and “confirm_clients” in confirm_clients columns t.column :client_id, :string t.column: agent_id, :string t.column:confirm, :boolean

agents t.column :agent_id, :string t.column :rank, :integer

i want to count the occurence of each agent_id ,which the confirm boolean is “true” and i want to save that count number in the rank column of agents an example

if confirm_clients table agent_id=agent1 has 4 boolean true rows so i want to save 4 in the agents table rank column,corresponding agent1s row.plz can anyone help me to solve this problem

Just do:

agent.confirm_clients.count([“confirm = ?”, true])