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inserting data into a dependent table

Hello,

I have two tables, one is a list of activities, the other a list of
participants. I want to insert one record in the activities table and
then using its identity column as foreign key, I want to insert two or
more records into the participants table.

My problem is that I have no idea what foreign key to use when
inserting names into the participants table. How can I get hold of the
row's key or identity column, immediately after inserting a row into
the activity table?

Thanks in advance.

Ahmet
Jul 8 '08 #1
5 5285
dos360 wrote:
Hello,

I have two tables, one is a list of activities, the other a list of
participants. I want to insert one record in the activities table and
then using its identity column as foreign key, I want to insert two or
more records into the participants table.

My problem is that I have no idea what foreign key to use when
inserting names into the participants table. How can I get hold of the
row's key or identity column, immediately after inserting a row into
the activity table?
The best way is to do a "SELECT FROM INSERT"
CREATE TABLE T(pk INT GENERATED ALWAYS AS IDENTITY, c1 INT);

SELECT pk FROM NEW TABLE(INSERT INTO T(c1) VALUES 10);
PK
-----------
1

1 record(s) selected.

You can also play with the IDENTITY_VAL_LOCAL() function, but that means
an extra SQL statement.
--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab
Jul 8 '08 #2
On Jul 8, 2:39 am, dos360 <vtam...@yahoo.comwrote:
Hello,

I have two tables, one is a list of activities, the other a list of
participants. I want to insert one record in the activities table and
then using its identity column as foreign key, I want to insert two or
more records into the participants table.

My problem is that I have no idea what foreign key to use when
inserting names into the participants table. How can I get hold of the
row's key or identity column, immediately after inserting a row into
the activity table?

Thanks in advance.

Ahmet
Try SELECT FROM OLD TABLE(INSERT INTO activities ...), you can read up
on it here: http://www.ibm.com/developerworks/db...dm-0411rielau/

Regards,
Miro
Jul 9 '08 #3
Thank you Serge,

It worked like a charm on my DB2 command editor, but not in my
program. Instead of returning one line with incremented identity
column contents, its returning zeros. At first one zero, then two
zeros, then three...

There were no errors in my sql statement so I thought, perhaps it
needs to be committed. So I went back to the Control Center and
discovered that my table T was still blank. Once I commit in the
command editor, I get a blank table T!

Sorry, I'm a little new to this.

Ahmet

On 8 Temmuz, 14:08, Serge Rielau <srie...@ca.ibm.comwrote:
dos360 wrote:
Hello,
I have two tables, one is a list of activities, the other a list of
participants. I want to insert one record in the activities table and
then using its identity column as foreign key, I want to insert two or
more records into the participants table.
My problem is that I have no idea what foreign key to use when
inserting names into the participants table. How can I get hold of the
row's key or identity column, immediately after inserting a row into
the activity table?

The best way is to do a "SELECT FROM INSERT"
CREATE TABLE T(pk INT GENERATED ALWAYS AS IDENTITY, c1 INT);

SELECT pk FROM NEW TABLE(INSERT INTO T(c1) VALUES 10);
PK
-----------
1

1 record(s) selected.

You can also play with the IDENTITY_VAL_LOCAL() function, but that means
an extra SQL statement.
--
Serge Rielau
DB2 Solutions Development
IBM Toronto Lab
Jul 9 '08 #4
>I have two tables, one is a list of Activities, the other a list of Participants. I want to insert one record [sic: rows are not records] in the Activities table and then using its IDENTITY column [sic IDENTITY is not a column, but a property of the physical storage] as foreign key [sic: IDENTITY cannot be a key by definition], I want to insert two or more records [sic] into the Participants table.<<

Please post DDL so we don't have to guess about the schema, if you
want help. Here is a guess at a properly designed schema:

CREATE TABLE Activities
(activity_id INTEGER NOT NULL PRIMARY KEY
activity_name CHAR(15) NOT NULL,
etc.)

CREATE TABLE Participants
(participant_id INTEGER NOT NULL PRIMARY KEY,
participant_name CHAR(15) NOT NULL,
etc.);

Participation is a relationship and will needs its own table

CREATE TABLE Participation
(participant_id INTEGER NOT NULL
REFERENCES Participants (participant_id)
ON DELETE CASCADE
ON UPDATE CASCADE,
activity_id INTEGER NOT NULL
REFERENCES Activities (activity_id)
ON DELETE CASCADE
ON UPDATE CASCADE,
PRIMARY KEY (participant_id, activity_id),
etc.);
>My problem is that I have no idea what foreign key to use when inserting names into the Participants table. How can I get hold of the row's key or IDENTITY column [sic], immediately after inserting a row into the activity table? <<
That is the wrong question: you don't use IDENTITY and you don't make
an entity into an attribute. You use a relationship table. If you had
Books and Authors, you would not make a book an attribute of an author
-- it does not grow out of his chest, does it? You would have an
Authorship table.
Jul 9 '08 #5
Thank you Celko. I see your point, if I had an association table
called participation I would be able to generate more reports.
Actually, I was trying to do something much simpler. First the DDL

create table ahmet.activity
(act_no bigint generated always as identity,
act_date DATE NOT NULL, etc)

create table ahmet.act_participant
(part_act_no bigint generated always as identity,
part_act_no bigint, <<<< "primary key of activity table goes here"
part_act_salesrep char(40))

My idea was first to insert a row (why can't a say a record then?)
into the activity table, then get hold of its primary key (act_no) and
then using it as a foreign key, to insert as many participants into
the second table (act_participant).

Serge said "use a select from insert" but for some reason it only
works (returns incremented results) in the command editor and even
then the rows aren't actually inserted because the table remains
blank. In my Lotus Notes clients basic code, it doesn't even return
incremented keys.

Any suggestions? With or without a third association table?

Ahmet

On Jul 9, 6:44*pm, --CELKO-- <jcelko...@earthlink.netwrote:
I have two tables, one is a list of Activities, the other a list of Participants. I want to insert one record [sic: rows are not records] in the Activities table and then using its IDENTITY column [sic IDENTITY is not a column, but a property of the physical storage] as foreign key [sic: IDENTITY cannot be a key by definition], I want to insert two or more records [sic] into the Participants table.<<

Please post DDL so we don't have to guess about the schema, if you
want help. *Here is a guess at a properly designed schema:

CREATE TABLE Activities
(activity_id INTEGER NOT NULL PRIMARY KEY
*activity_name CHAR(15) NOT NULL,
*etc.)

CREATE TABLE Participants
(participant_id INTEGER NOT NULL PRIMARY KEY,
*participant_name CHAR(15) NOT NULL,
*etc.);

Participation is a relationship and will needs its own table

CREATE TABLE Participation
(participant_id INTEGER NOT NULL
* *REFERENCES Participants (participant_id)
* *ON DELETE CASCADE
* *ON UPDATE CASCADE,
*activity_id INTEGER NOT NULL
* *REFERENCES Activities (activity_id)
* *ON DELETE CASCADE
* *ON UPDATE CASCADE,
*PRIMARY KEY (participant_id, activity_id),
* etc.);
My problem is that I have no idea what foreign key to use when inserting names into the Participants table. How can I get hold of the row's key or IDENTITY column [sic], immediately after inserting a row into the activity table? <<

That is the wrong question: you don't use IDENTITY and you don't make
an entity into an attribute. *You use a relationship table. If you had
Books and Authors, you would not make a book an attribute of an author
-- it does not grow out of his chest, does it? *You would have an
Authorship table.
Jul 10 '08 #6

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