Joining msg.payload and then sending to SQLite. Two entries instead of one

Hi there,

I'm very new to node red so apologies in advance if I make a mis-step with posting for help. My question outlined here, is how do I get two MQTT messages to input into an SQLite database as a single entry.

I have followed a number of youtube tutorials and almost everything works as expected. My current problem is...

I have an ESP32 reading temperature and humidity simultaneously, they are coming across separately via different MQTT threads for Node Red dashboard. This is working fine.

Temperature MQTT and a Humidity MQTT message are then both set to a function to change the msg.topic to Temperature and Humidity (respectively). These function nodes go into 'join' with a manual setup, setting combine each msg.payload to create a key/value using the value of msg.topic as the key. It is set to send the message after every 2 message parts. The debug from this fires once and is as follows;

30/10/2022, 19:09:13node: debug 17Humidity : msg.payload : Object

{ Temperature: 23.2, Humidity: 64.5 }

From this I take that the join is working fine as both values come across as one message. From here the join I go into a function node with the following; (Which I put together from the ChilliChump YouTube tutorial on MQTT and SQLite).

var sqliteTimeStamp = Math.round( / 1000);
var theDevice = "Lounge";
// var theSensor = "Humidity";

var theSQL = "INSERT INTO Test1 (Date_Time, Area, Temperature, Humidity) VALUES "
theSQL = theSQL + "('" + sqliteTimeStamp + "', '" + theDevice + "', " + msg.payload.Temperature +", " + msg.payload.Humidity + "  );" ;
msg.topic = theSQL;

return msg;

The debug of this function gives me this;

30/10/2022, 19:14:34node: debug 16INSERT INTO Test1 (Date_Time, Area, Temperature, Humidity) VALUES ('1667157274', 'Lounge', 23.3, 64.6 ); : msg.payload : Object

{ Temperature: 23.3, Humidity: 64.6 }

From this I take it that an INSERT into the table has both values in a single SQL insert ... "message". However when I look at the SQL Database, I'm seeing that the values are separated out into two entries.

ID	Date_Time	Area	Temperature	Humidity
455	1667155259	Lounge	22.5	NULL
456	1667155259	Lounge	NULL	65.8
457	1667155269	Lounge	22.5	NULL
458	1667155269	Lounge	NULL	65.8
459	1667155279	Lounge	22.5	NULL
460	1667155279	Lounge	NULL	65.8

As you can hopefully see, the SQL isn't getting or perhaps treating the message as a joint 'package' and is separating out to two ID's the values that should come across as one.

I've done alot of googling and watched many tutorials. As you can hopefully see I've at least fixed the common mistakes and the data is going into the fields but not 100% as expected. What I'm hoping to achieve is a single SQL entry with both values populated to avoid NULL and duplicate entries.

As a new user I'm not sure what else I can supply to help trouble shoot this. So please do let me know if more information is uploaded. But I'm also a new user so suspect I will be limited in the number of responses and what I can upload.

Many thanks.


What does the record for that time show?

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As per your suggestion, and you pointed it out quite clearly, that specific entry wasn't in the database which clearly highlights an issue. I traced it back to the most stupid of errors, I hadn't linked the function and the SQL insert function, it was still hooked to an earlier test.

My forehead has a definite palm shaped red mark!

ID Date_Time Area Temperature Humidity
1514 1667160583 Lounge 23.8 64.4
1515 1667160593 Lounge 23.8 64.4
1516 1667160603 Lounge 23.8 64.4
1517 1667160613 Lounge 23.8 64.4
1518 1667160623 Lounge 23.8 64.4

@Colin Thanks for the hint to look for the specific time code quoted in Node-Red and SQLite!!! That helped me trace the error!

Thanks again

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