Sql query for multiple tables of SQLite - sql

Question

I have an SQL database (pq) with 3 tables as sample is shown in image. I am trying to achieve below things:
Select only rows with variable P from the MEASUREMENT column in Table 3. I tried below query but it didnt produced the correct output.
select distinct pq_data.READ_TIME,OBS_METER,MEASUREMENT,VALUE from pq_data ORDER BY MEASUREMENT;
Then, fetch the data columns CUST_CLASS, and SOLAR from Table 1 into Table 3 according to OBS_METER id. The OBS_METER column is not available in Table 1 but the it can be obtained from OBS_LOCATION in Table 2.
The expected output of SQL query is Table 3 with additional columns from other tables,such as:
row id READ_TIME OBS_METER OBS_LOCATION MEASUREMENT VALUE CUST_CLASS SOLAR
28/01/2018 2018/01/28 01:55:00 105714 6787 P 284 R F
..........
I searched for existing answers: 1 , 2 but I couldnt able to write a SQL query which will produce above expected output.

Answer 1

Select only rows with variable P from the MEASUREMENT column in Table 3.
select * from pq_data WHERE MEASUREMENT='P';
Then, fetch the data columns CUST_CLASS, and SOLAR from Table 1 into
Table 3 according to OBS_METER id.
select *
from pq_data pd
inner join meter_mapping mm on pd pd.obs_meter=mm.obs_meter
inner join location_mapping lm on mm.obs_location=lm.obs_location
WHERE pd.MEASUREMENT='P'
The expected output of SQL query is Table 3 with additional columns
from other tables:
You did not specify which table is the rowid that you wanted, I assumed that it was from pq_data.
Also, I don't know if an entry on pq_data will always have a match in meter_mapping (and location_maping). If it don't you need to use "left join" (or right).
It would be easier if you used the actual name of the tables in your questions (instead of table 1, 2 and 3).
select pd.rowid, pd.READ_TIME, pd.OBS_METER, mm.OBS_LOCATION, pd.MEASUREMENT, pd.VALUE, lm.CUST_CLASS, lm.SOLAR
from pq_data pd
inner join meter_mapping mm on pd pd.OBS_METER=mm.OBS_METER
inner join location_mapping lm on mm.OBS_LOCATION=lm.OBS_LOCATION
WHERE pd.MEASUREMENT='P'