this is een extraxt of my sqlite3 db feeded by mqtt - 4th field is the Fnct : we see a jump from 732 to 734 and 733 missing

4614|2021-07-09 06:53:40.210159|1884.0|732.0|-37.0|3.299|A|2021-07-09T04:53:39.905630893Z
4615|2021-07-09 07:03:40.208637|1884.0|734.0|-39.0|3.29|A|2021-07-09T05:03:39.916213247Z


following is an extract of the gateway log where we see the "FCnt": 733 appearing (line 37); I assume the preceding lines (line 8 to 36 handle about the packet from the sensor.

Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]:
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ################## Report at: 2021-07-09 04:58:31 UTC ##################
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ### [UPSTREAM] ###
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # RF packets received by concentrator: 0
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # CRC_OK: 0.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # RF packets forwarded: 0 (0 bytes)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PUSH_DATA datagrams sent: 0 (0 bytes)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PUSH_DATA acknowledged: 0.00%
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ### [DOWNSTREAM] ###
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PULL_DATA sent: 1 (100.00% acknowledged)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PULL_RESP(onse) datagrams received: 0 (0 bytes)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # RF packets sent to concentrator: 0 (0 bytes)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX errors: 0
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (collision packet): 0.00% (req:8, rej:0)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (collision beacon): 0.00% (req:8, rej:0)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (too late): 0.00% (req:8, rej:0)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (too early): 0.00% (req:8, rej:0)
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # BEACON queued: 0
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # BEACON sent so far: 0
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # BEACON rejected: 0
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ### [PPS] ###
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # SX1301 time (PPS): 2628362402
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: INFO: [jit] queue is empty
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: INFO~ ### [GPS] ###
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: INFO~ # GPS sync is disabled
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: INFO~ ##### END #####
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: RXTX~ {"stat":{"time":"2021-07-09 04:58:31 UTC","rxnb":0,"rxok":0,"rxfw":0,"ackr":0.0,"dwnb":0,"txnb":0}}
Fri Jul  9 05:58:31 2021 daemon.info lora_pkt_fwd[31208]: INFO~ [up] PUSH_ACK received in 31 ms
Fri Jul  9 05:58:39 2021 daemon.info lora_pkt_fwd[31208]: PKT_FWD~ DATA_UNCONF_UP-> {"DevAddr": "260BC4C3", "FCtrl": ["ADR": 1, "ADRACKReq": 0, "ACK": 0, "RFU" : "RFU", "FOptsLen": 0], "FCnt": 733, "FPort": 2, "MIC": "B40D9C52"}
Fri Jul  9 05:58:39 2021 daemon.info lora_pkt_fwd[31208]: RXTX~ {"rxpk":[{"tmst":2640915467,"time":"2021-07-09T04:58:39.894904Z","chan":3,"rfch":0,"freq":867.100000,"stat":1,"modu":"LORA","datr":"SF7BW125","codr":"4/5","lsnr":10.5,"rssi":-39,"size":18,"data":"QMPECyaA3QICXZ1XlD5SnA20"}]}
Fri Jul  9 05:58:39 2021 daemon.info lora_pkt_fwd[31208]: INFO~ [up] PUSH_ACK received in 31 ms
Fri Jul  9 05:58:42 2021 user.notice iot_keep_alive: Internet Access OK: via wlan0-2
Fri Jul  9 05:58:42 2021 user.notice iot_keep_alive: use WAN or WiFi for internet access now
Fri Jul  9 05:58:53 2021 daemon.info lora_pkt_fwd[31208]: INFO~ [down] PULL_ACK received in 33 ms
Fri Jul  9 05:58:58 2021 user.notice iot_keep_alive: Internet Access OK: via wlan0-2
Fri Jul  9 05:58:58 2021 user.notice iot_keep_alive: use WAN or WiFi for internet access now
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]:
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ################## Report at: 2021-07-09 04:59:01 UTC ##################
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ### [UPSTREAM] ###
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # RF packets received by concentrator: 1
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # CRC_OK: 100.00%, CRC_FAIL: 0.00%, NO_CRC: 0.00%
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # RF packets forwarded: 1 (18 bytes)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PUSH_DATA datagrams sent: 1 (236 bytes)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PUSH_DATA acknowledged: 100.00%
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ### [DOWNSTREAM] ###
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PULL_DATA sent: 1 (100.00% acknowledged)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # PULL_RESP(onse) datagrams received: 0 (0 bytes)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # RF packets sent to concentrator: 0 (0 bytes)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX errors: 0
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (collision packet): 0.00% (req:8, rej:0)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (collision beacon): 0.00% (req:8, rej:0)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (too late): 0.00% (req:8, rej:0)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # TX rejected (too early): 0.00% (req:8, rej:0)
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # BEACON queued: 0
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # BEACON sent so far: 0
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # BEACON rejected: 0
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ ### [PPS] ###
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: REPORT~ # SX1301 time (PPS): 2628362402
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: INFO: [jit] queue is empty
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: INFO~ ### [GPS] ###
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: INFO~ # GPS sync is disabled
Fri Jul  9 05:59:01 2021 daemon.info lora_pkt_fwd[31208]: INFO~ ##### END #####


From this morning - missing 1078 (4 th field)
4948|2021-07-10 11:38:42.549344|1876.0|1077.0|-31.0|3.301|A|2021-07-10T09:38:42.190202568Z
4949|2021-07-10 11:48:42.463892|1876.0|1079.0|-35.0|3.292|A|2021-07-10T09:48:42.140412587Z

In this case I do have no extract from the gateway log as I have to retrieve this with a putty session which is not always running. But last field is the timestamp from the retrieved mqtt 
record and the DevAddr is always the same. Probably that's enough to query your database.