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copied!<p>This is the sequence solution (for postgres), you'd have to do it in a stored procedure or on your application code, of course.</p> <pre><code>postgres=# create table foo(id serial primary key, text varchar); NOTICE: CREATE TABLE will create implicit sequence "foo_id_seq" for serial column "foo.id" NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "foo_pkey" for table "foo" CREATE TABLE postgres=# create table bar(id int references foo, text varchar); CREATE TABLE postgres=# select nextval('foo_id_seq'); nextval --------- 1 (1 row) postgres=# insert into foo values (1,'a'); insert into bar values(1,'b'); INSERT 0 1 INSERT 0 1 </code></pre> <p>For <a href="http://dev.mysql.com/doc/refman/5.0/en/getting-unique-id.html" rel="nofollow noreferrer">MySQL</a>, the transaction is important not to trip on your own feet in case you're using the same connection for more than one insert.</p> <blockquote> <p>For LAST_INSERT_ID(), the most recently generated ID is maintained in the server on a per-connection basis. It is not changed by another client. It is not even changed if you update another AUTO_INCREMENT column with a non-magic value (that is, a value that is not NULL and not 0). Using LAST_INSERT_ID() and AUTO_INCREMENT columns simultaneously from multiple clients is perfectly valid. Each client will receive the last inserted ID for the last statement that client executed.</p> </blockquote> <pre><code>mysql> create table foo(id int primary key auto_increment, text varchar(10)) Engine=InnoDB; Query OK, 0 rows affected (0.06 sec) mysql> create table bar(id int references foo, text varchar(10)) Engine=InnoDB; Query OK, 0 rows affected (0.01 sec) mysql> begin; Query OK, 0 rows affected (0.00 sec) mysql> insert into foo(text) values ('x'); Query OK, 1 row affected (0.00 sec) mysql> insert into bar values (last_insert_id(),'y'); Query OK, 1 row affected (0.00 sec) mysql> commit; Query OK, 0 rows affected (0.04 sec) </code></pre>

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