Shruthi A wrote:
> I have 2 tables (A and B) where the table B has a foreign key reference to
> table A. Like this:
> create table A (x int primary key);
> create table B (y int primary key, z int references A (x) );
> As you can see, i've not specified any further 'on delete' clause to the
>
Hello,
I have 2 tables (A and B) where the table B has a foreign key reference to
table A. Like this:
create table A (x int primary key);
create table B (y int primary key, z int references A (x) );
As you can see, i've not specified any further 'on delete' clause to the
foreign key constraint
Louis-David Mitterrand wrote:
> Here is my schema:
> cruise_line -> ship(id_line) -> cruise_type(id_ship) -> cruise(id_cruise_type)
> -> price(id_cruise, id_currency) <- currency (USD,GBP,EUR,CAD)
> (a 'cruise' is a 'cruise_type' + a date)
> I am trying to display a count of cruise's for
Hi,
Here is my schema:
cruise_line -> ship(id_line) -> cruise_type(id_ship) -> cruise(id_cruise_type)
-> price(id_cruise, id_currency) <- currency (USD,GBP,EUR,CAD)
(a 'cruise' is a 'cruise_type' + a date)
I am trying to display a count of cruise's for each ship and each
currency even
Yes, because your WHERE is something that comes after the operation
of the LEFT JOIN, in practice, defeating the purpose you intented.
On your second query the p.id_line = 1 doesn't do that because it is part of
the LEFT JOIN itself..
HTH
Best,
Oliveiros d'Azevedo Cristina
- Original Mes
On Fri, Feb 12, 2010 at 11:35:02AM -, Oliveiros C, wrote:
> My first guess is that
> NULL fails the condition on your WHERE clause,
> p.id_line = 1
>
> So your WHERE clause introduces an additional level of filtering
> that filters out the NULLs coming from the LEFT JOIN...
So, if I understan
> where p.id_line=1
this filters rows after join was applied. Try this
select c.id_currency,max(p.modified_on) from currency c left join
price_line p using (id_currency) where (p.id_line=1 or p.id_line is null) group
by
c.id_currency;
> Hi,
> This query:
> select c.id_currency,max(p.modif
My first guess is that
NULL fails the condition on your WHERE clause,
p.id_line = 1
So your WHERE clause introduces an additional level of filtering that
filters out the NULLs coming from the LEFT JOIN...
Didn't do any tests, it's just a guess...
Best,
Oliveiros
- Original Message -
Hi,
This query:
select c.id_currency,max(p.modified_on) from currency c left join
price_line p using (id_currency) where p.id_line=1 group by
c.id_currency;
doesn't list all c.id_currency's, only those with a price_line. However
this one does:
select c.id_currency,max(p.modified_on) from curren
