To use the add SUB Function
SUB(TagTag1,TagTag2,Tag)Tag3)
Tag1 - Tag2 - Tag3
SUB(Demo-influxdb/DEMO_01TI031.PV,Demo-influxdb/DEMO_01TI032.PV,Demo-influxdb/DEMO_01TI021.PV)
To use the add SUB Function
SUB(TagTag1,TagTag2,Tag)Tag3)
Tag1 - Tag2 - Tag3
SUB(Demo-influxdb/DEMO_01TI031.PV,Demo-influxdb/DEMO_01TI032.PV,Demo-influxdb/DEMO_01TI021.PV)