On Tuesday 09 December 2003 15:41, Bahadir ARMAGAN wrote:

> I have an integer field that an application increments it each time
> it adds a record. But when I run the intances of that application at
> the same time , I get an error because all the instances reading the
> same last value and trying to insert the same incremented value to
> this unique field.
>
> What is the general methode that is to be followed for this problem?
> Is it possible to create an autoincrement field as in access
> databases? What if I try to make a field (already have unique recodrs
> in it) autoincrement?

ok, assume this table:

create table TEST123 (
ID INTEGER NOT NULL PRIMARY KEY,
NAME VARCHAR(100)
);

and you want ID to be autoincremented.
Follow these steps:

1. Create a generator:
CREATE GENERATOR MY_GEN;
2. Set it's value to the higest ID already used in your DB:
SET GENERATOR MY_GEN TO 1234;
(if you omit this step, ID will start at 1 with the first insert)
3. Use this syntax when you insert a record:
INSERT INTO TEST123 (ID,NAME) VALUES (GEN_ID(MY_GEN,1),'blablabla');

Find a record with ID=1235 and NAME='blablabla' in your DB.

(Of course you could also use a trigger. With a trigger you would not
need to specify the ID column in the insert statement (See message from
Richard Pendered), so your insert would be like this:
INSERT INTO TEST123 (NAME) VALUES ('blablabla');
Youself decide whether this is an advantage for you or not.)

regards,
Yves Glodt

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