Postgis nested query trouble

Question

I am having difficulty writing a nested postgis query. I have a single table from which I need to create a view in PostgreSQL.

I have created the view with the following command

create view rrop08.rrop08_lws_f AS
select * from rrop08.rrop08_gk3_polygon 
where planznr='04.01' OR planznr ='04.02';

The problem here is that the table contains another field called "bez". I need to carry out the first query but also with bez=0; so that none of the 04.01 or 04.02 rows have a bez value other than 0.

I have tried this...

create view rrop08.rrop08_lws_f AS
select * from rrop08.rrop08_gk3_polygon 
where planznr='04.01' OR planznr ='04.02' AND bez=0;

but this retrieves all rows with bez=0 and not just the 04.01 or 04.02 ones. I need to first select 04.01 or 04.02 and then on this query get those with bez=0...ie.nested.

I´m a bit lost on how to do this.

THanks for any help,

Rob

Answer 1

Use parenthesis to group the logical expressions or they usually get evaluated from left to right like you experienced:

create view rrop08.rrop08_lws_f AS select * from rrop08.rrop08_gk3_polygon where (planznr='04.01' OR planznr ='04.02') AND bez=0;