SQL Query: How to add last check-in time

I'm aware that dbo.InventoryReport.LastCheckInTime will give the last time SEP checked into parent server.

But I cannot find a common key in the dbo.InventoryReport that will interoperate with commonly used tables/fields.

See SQL query where I'd like to add column for dbo.InventoryReport.LastCheckInTime

SELECT dbo.sem_computer.COMPUTER_NAME,
    [IP_ADDR1_TEXT],dbo.sem_computer.COMPUTER_DOMAIN_NAME,             dbo.SEM_COMPUTER.OPERATION_SYSTEM,NAME,dbo.SEM_AGENT.AGENT_VERSION, 
    Convert(VARCHAR(12),DBO.PATTERN.PATTERNDATE,107) as Antivirus_Date,
    CASE dbo.SEM_AGENT.STATUS 
       WHEN 0 THEN 'Offline'
       WHEN 1 THEN 'Online'
    END AS Status
    FROM dbo.sem_computer, [dbo].[V_SEM_COMPUTER], dbo.IDENTITY_MAP, dbo.SEM_CLIENT,dbo.SEM_AGENT,dbo.PATTERN
    WHERE [dbo].[V_SEM_COMPUTER].COMPUTER_ID = SEM_COMPUTER.COMPUTER_ID
    AND dbo.SEM_CLIENT.GROUP_ID = IDENTITY_MAP.ID
    AND dbo.SEM_CLIENT.COMPUTER_ID = SEM_COMPUTER.COMPUTER_ID
    AND SEM_COMPUTER.COMPUTER_ID = dbo.SEM_AGENT.COMPUTER_ID
    AND dbo.PATTERN.PATTERN_IDX = dbo.SEM_AGENT.PATTERN_IDX