In[]:=
test=Tabular[{"location""study","temperaturesensor""SHTC3","location""basement","temperaturesensor""BME280","location""familyroom","temperaturesensor""BME280","location""Study","temperaturesensor"Missing["NotAvailable"],"location""DiningRoom","temperaturesensor""MCP9808","location""upstairs","temperaturesensor""MCP9808","location""Thermostat","temperaturesensor""DPS310","location""FamilyTV","temperaturesensor""TMP117","location""Indeterminate","temperaturesensor""BME680","location""LaniStudy","temperaturesensor""BME680","location""Basement","temperaturesensor""BME680"}];
Select[test,(#["location"]=="familyroom"&)]
Out[]=
Tabular
In[]:=
testKey="location";Normal[Select[test,(#[testKey]=="familyroom"&)]]
Out[]=
{}