Question

I would like to insert data into multiple tables if an entry does not exist.

In my case I have a restaurant table, a location table, a foodtype table and some helper tables like restaurant_location, and restaurant_foodtype. Now I would like to insert a new restaurant entry complete with the location and the foodtype info if the entry does not exist.

So something like:

IF NOT (select 1 from restaurant where name='restaurantname') THEN
 INSERT INTO restaurant(x,y) VALUES (valuex,valuey);
 INSERT INTO restaurant_location(rest_id,..) VALUES (rest_id,..);
 INSERT INTO restaurant_foodtype(rest_id,..) VALUES (rest_id,..);
 ...
END IF

How can I do this with simple SQL?

Answer 1

I just wrote this at the top of my head but this should be the idea, if you must do it with simple sql.

insert into 
    restaurant(x, y)
values
    select valuex, valuey 
    from dual
    where
      not exists(
        select 1 from restaurant where name = 'restaurantname')

---

EDIT:
Again, I couldn’t parse it but you probably could make use of the WITH clause:

with validation as(
  select 1 from restaurant where name = 'restaurantname'
)
insert into 
    restaurant(x, y)
values
    (
     select value1x, value1y 
     from dual
     where
       validation.v = 1),
    (
     select value2x, value2y 
     from dual
     where
       validation.v = 1)