Well, I think an update after insert is the only way. Other than perpopulating another table with possibe crc values then usinga join: Select id from testtable Inner join crctable on testtable.id=3Dcrctable.id Where crctable.crcval=3D'xxxxxxx' Just be sure to index the crcval column. On Sunday, May 3, 2009, thunder@isfahan.at <thunder@isfahan.at> wrote: > Hi Johnny, > > I need the CRC32 for a unique URL-ID... > > I think it isn't to slow when I make a SELECT later in this form: > > Rows in Table: 825,984 > > Search for id: 2532552 (CRC32: 46316330) > > SELECT id FROM `testtable` WHERE id =3D "2532552" > 0.0005 sec. > > SELECT id FROM `testtable` WHERE CRC32(id) =3D "46316330" > 0.5712 sec. > > OK, I can make an UPDATE after an INSERT but then I can't use UNIQUE for = the Coloumn with the CRC32... > Before I can make an Update, the Value is 0... > > > > I don't think its possible to do what you want in a single statement. Sin= ce > LAST-INSERT-ID() is set to the last insert id of the connection... and th= e > row you are inserting doesn't exist.. well.. until you create it, it will > always either be zero or the record BEFORE your next insert, ie: > > INSERT INTO testtable(NULL,LAST-INSERT-ID()); > INSERT INTO testtable(NULL,LAST-INSERT-ID()); > > would produce > ID =A0 =A0CRC32ID > 1 =A0 =A0 =A0 0 > 2 =A0 =A0 =A0 1 > > You could run an update immediately after the insert to set the CRC32 > column: > > UPDATE testtable SET id-crc=3DCRC32(LAST-INSERT-ID()) WHERE > id=3DLAST-INSERT-ID(); > > Not quite sure why you need the CRC32 value of the ID, will it not always= be > the same value for the given ID number? Wouldn't it be easier to do it on > the select side of the equation? > > SELECT id,CRC32(id) AS id-crc... FROM testtable... > > -jw > On Sun, May 3, 2009 at 7:16 AM, thunder@isfahan.at <thunder@isfahan.at>wr= ote: > > > > Hello, > I have a questions and I hope, that is possible in MySQL. > > I have the following short Table. > CREATE TABLE IF NOT EXISTS `testtable` ( > =A0`id` bigint(20) unsigned NOT NULL auto-increment, > =A0`id-crc` bigint(20) unsigned NOT NULL, > =A0PRIMARY KEY =A0(`id`), > =A0UNIQUE KEY `id-crc` (`id-crc`) > ) ENGINE=3DMyISAM =A0DEFAULT CHARSET=3Dlatin1 AUTO-INCREMENT=3D1 ; > > > `id` is the unique autoincrement > > in `id-crc` I would like save the CRC32 from `id` (the coloumn is unique) > > E.G. > > id =A0 =A0 =A0id-crc > ---------------------------