Make nested SQL queries

Question

I want to do a Nested query to add the same data but with different filters. I have tried something like this but that gives nothing or doesn't execute:

Select ENFACT.NUMFACT, CLIENT.NOM ,ENFACT.MONTMONTTC ,ECHEANC.DATEECHÉANCE AS DATE1, (Select ECHEANC.DATEECHÉANCE From ECHEANC ) AS DATE2 
From CLIENT, ENFACT, ECHEANC 
Where ENFACT.COCLI=CLIENT.COCLI 
And ENFACT.NUMFACT=ECHEANC.NUMFACT 
And ENFACT.TYPEFAC='F'

Answer 1

I think this is what you are trying to do

Select ENFACT.NUMFACT, CLIENT.NOM ,ENFACT.MONTMONTTC ,ECHEANC.DATEECHÉANCE AS DATE1, ECHEANC.DATEECHÉANCE AS DATE2 
From CLIENT inner join ENFACT 
on ENFACT.COCLI=CLIENT.COCLI 
inner join  ECHEANC
on ENFACT.NUMFACT=ECHEANC.NUMFACT 
where ENFACT.TYPEFAC='F'

You don't need a subquery, just a join between 3 tables. Up to you to choose between left or inner join, I used inner join in my example