Looks good.
Now the copied path is: payload.uplink_message.decoded_payload.messages[0].measurementValue
Don't know where the [0] came from but will see if it works.
You beauty it works. Thanks guys. Here is my decode for completeness.
msg.baro = msg.payload.uplink_message.decoded_payload.messages[0].measurementValue; msg.topic = "INSERT INTO TTNsensors(barometrics) VALUES('"+msg.baro + "');" return msg;