Using MAX function in a subquery in Access - sql

Question

In Microsoft Access, I'm querying data from four tables and I'm using the MAX function to display the most recent records. The code below works but it's using two queries linked together. By using a sub-query, shown below with the full code, the code takes an hour to run, which is why I using two queries. Is there a better way of doing this?
QUERY 1
SELECT
a.office_id AS ofid,
rc.recorder_id AS recorder,
a.cust_name,
r.account_id,
rc.lpc_phone,
rc.device_serial,
rc.device_mfg,
rc.device_type
INTO RDS_INFO
FROM MaxDates
INNER JOIN (status AS s INNER JOIN ((config_recorder AS rc INNER JOIN recorders AS r ON rc.recorder_id = r.recorder_id)
INNER JOIN accounts AS a ON r.account_id = a.account_id) ON s.status = rc.row_status) ON (MaxDates.MaxOftrans_datetime = rc.trans_datetime) AND (MaxDates.recorder_id = rc.recorder_id)
WHERE (((rc.lpc_phone) Is Not Null
And (rc.lpc_phone)<>" "
And (rc.lpc_phone) Not Like "#,*")
AND ((rc.call_mode)="AN")
AND ((rc.row_status)=3
Or (rc.row_status)=11));
MaxDates Query:
SELECT
config_recorder.recorder_id,
Max(config_recorder.trans_datetime) AS MaxOftrans_datetime
FROM config_recorder
GROUP BY config_recorder.recorder_id;
Code used with the sub-query:
SELECT
a.cycle AS cyc,
a.office_id AS ofid,
rc.recorder_id AS recorder,
a.cust_name,
r.account_id,
rc.lpc_phone,
rc.device_serial,
rc.device_mfg,
rc.device_type
INTO Test
FROM config_recorder AS rc, status AS s, recorders AS r, accounts AS a
WHERE rc.recorder_id=r.recorder_id
AND r.account_id=a.account_id
AND ((rc.lpc_phone Is Not Null)
AND (rc.lpc_phone<>" ")
AND (rc.lpc_phone Not Like "#,*"))
AND ((rc.call_mode="AN")
AND (rc.row_status=s.status)
AND ((rc.row_status="3")
Or (rc.row_status="11")))
AND (rc.trans_datetime=(select max(r2.trans_datetime) from config_recorder r2 where r2.recorder_id = rc.recorder_id));
Thank you for your help.

Answer 1

You can consider changing the sub-query into an inline view and then joining it with other tables, as below:
SELECT
a.office_id AS ofid,
rc.recorder_id AS recorder,
a.cust_name,
r.account_id,
rc.lpc_phone,
rc.device_serial,
rc.device_mfg,
rc.device_type
INTO RDS_INFO
FROM status AS s
INNER JOIN
(config_recorder AS rc INNER JOIN recorders AS r ON rc.recorder_id = r.recorder_id)
ON s.status = rc.row_status
INNER JOIN accounts AS a
ON r.account_id = a.account_id
INNER JOIN
(SELECT
config_recorder.recorder_id,
Max(config_recorder.trans_datetime) AS MaxOftrans_datetime
FROM config_recorder
GROUP BY config_recorder.recorder_id) MaxDates
ON (MaxDates.MaxOftrans_datetime = rc.trans_datetime) AND (MaxDates.recorder_id = rc.recorder_id)
WHERE (((rc.lpc_phone) Is Not Null
And (rc.lpc_phone)<>" "
And (rc.lpc_phone) Not Like "#,*")
AND ((rc.call_mode)="AN")
AND ((rc.row_status)=3
Or (rc.row_status)=11));
References:
A related question on SO
Inline Views Versus Temp Tables on MSDN Magazine