> From: punk.k...@gmail.com
> Date: Mon, 4 Apr 2011 08:06:31 -0500
> To: sqlite-users@sqlite.org
> Subject: Re: [sqlite] Question:how to insert row with multiple values from
> same field of different rows of another table?
>
>
> On Apr 4, 2011, at 7:59 AM, Colin Cuthbert wrote:
>
> >
> >
> >
> >> From: punk.k...@gmail.com
> >> Date: Sun, 3 Apr 2011 07:52:42 -0500
> >> To: sqlite-users@sqlite.org
> >> Subject: Re: [sqlite] Question:how to insert row with multiple values from
> >> same field of different rows of another table?
> >>
> >>
> >> On Apr 3, 2011, at 7:50 AM, Luuk wrote:
> >>
> >>> On 03-04-2011 14:43, Colin Cuthbert wrote:
> >>>> First time I've used this (or any!) mailing list, so sorry if I've done
> >>>> something wrong.
> >>>>
> >>>> Pretty sure my question (in the subect) is phrased badly but it's the
> >>>> best I could do!
> >>>>
> >>>> create table People(id integer primary key, name text);
> >>>> insert into People (name) values ('bob');
> >>>> insert into People (name) values ('fred');
> >>>>
> >>>> create table Cars(id integer primary key, name text);
> >>>> insert into Cars (name) values ('ford');
> >>>> insert into Cars (name) values ('volvo');
> >>>>
> >>>> create table CarOwners(id integer primary key, carId integer references
> >>>> Cars(id), ownerId integer references People(id));
> >>>> insert into CarOwners (carId, ownerId) select Cars.id, People.id from
> >>>> Cars, People where Cars.name='ford' and People.name='bob';
> >>>>
> >>>> create table Couples(id integer primary key, personId1 integer
> >>>> references People(id), personId2 integer references People(id));
> >>>>
> >>>> The last 'insert' statement seems to work for inserting a row into the
> >>>> 'CarOwners' table, but I'm not sure that's the right/best way to do it.
> >>>>
> >>>> But how can I do a similar insert into the 'Couples' table? ie, how can
> >>>> I insert a row (specifying 'personId1' and 'personId2' via queries based
> >>>> on 'People.name') into the 'Couples' table?
> >>>
> >>> You forgot to define 'Couples'.....
> >>>> Does it start something like this?
> >>>>
> >>>> insert into Couples (personId1, personId2) select id, id from People
> >>>> where...
> >>>
> >>> select id, id from People will return the same id (from the same record)
> >>> twice....
> >>>
> >>> somehting like:
> >>> select a.id, b.id from People a join People b on a.id<>b.id
> >>> will give other results, but what youactually want to be returned
> >>> depends on the definition of a 'Couple'...
> >>>
> >>
> >> You also want to do all of the above in a TRANSACTION, preferably with a
> >> TRIGGER, to ensure the correct relationships are preserved.
> >
> > Ok I looked into transactions (I'm new to sql!). Isn't a transaction
> > automatically created with the insert statement? Or are you saying I need
> > to explicitly begin/end one as part of the solution to my problem?
>
>
> Yes, you need explicit BEGIN/END to perform a transaction.
>
> >
> > And regarding a trigger to ensure the correct relationships are
> > preserved... yeah you're right, but that's another issue isn't it? Or is
> > it related to this issue in a way that I'm not seeing?
>
> Another, but related issue.
>
> Regarding your original problem, the following works
>
> INSERT INTO Couples (personId1, personId2) VALUES ((SELECT id FROM People
> WHERE name = 'bob'), (SELECT id FROM People WHERE name = 'fred'));
> sqlite> SELECT * FROM Couples;
> id personId1 personId2
> ---------- ---------- ----------
> 1 1 2
>
Ha! You're brilliant! Thank you :)
I think I tried that but without the parentheses around the individual select
statements... would that have made a difference? Or maybe I didn't try that at
all :) Either way, thanks again!
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