auto-increment

I would like to achieve an identity or auto-incrementing value in a column ala SQL Server: CREATE TABLE RollingStock ( Id NUMBER IDENTITY(1,1), Name Varchar2(80) NOT NULL ); How can this be done? Matthew Watson As Orbman says, the standard way to do it is with a sequence. What most people also do is couple this with an insert trigger. So, when a row is inserted without an ID, the trigger fires to fill out the ID for you from the sequence. CREATE SEQUENCE SEQ_ROLLINGSTOCK_ID START WITH 1 INCREMENT BY 1 NOCYCLE; CREATE OR REPLACE TRIGGER BI_ROLLINGSTOCK BEFORE INSERT ON ROLLINGSTOCK REFERENCING

We want to obtain an auto-increment ID from mySQL without actually storing it until the other non-mysql related processes are successfully completed, so that the entry is not stored if an exception or application crash happens. We need to use the ID as a key for the other processes. In essence we want to “reserve” the auto-increment and insert the rows into mySQL as the last step. We don’t want to insert any row until we know the entire process has completed successfully. Is it possible to do this sort of auto-increment reservation in mySQL? Note: I know about the SQL transactions. But our

I need to add an auto increment id to an already existing table. I did: ALTER TABLE table_name ADD column_name INT NOT NULL AUTO_INCREMENT FIRST , ADD PRIMARY KEY (column_name) However, the auto numbering wasnt based on any particular column order. I want mysql to smartly put auto numbers based on the order of certain column. Is it possible? Most of the answers out there tell you how to add auto increment fields, not how to control those numbers in already existing table. Add a new field - ALTER TABLE table_name ADD column_name INT FIRTS; Populate data in the new field. Make this field as part

I'm using Hibernate to access MySQL, and I have a table with an auto-increment primary key. Everytime I insert a row into the table I don't need to specify the primary key. But after I insert a new row, how can I get the relative primary key immediately using hibernate? Or I can just use jdbc to do this? When you save the hibernate entity, the id property will be populated for you. So if you have MyThing thing = new MyThing(); ... // save the transient instance. dao.save(thing); // after the session flushes, thing.getId() should return the id. I actually almost always do an assertNotNull on

I am trying to find a record in mongoDB by it's MongoID "_id" field. I have found examples on how to do it, but can not get it to work. Example: $recID = "010101010101011"; //would be a valid mongodb _id $recID = new MongoId((string)$recID); // I have tried it without the (string) cast too $cursor = $this->Collection->findOne(array('_id' => $recID)); print_r($cursor); It outputs: MongoCursor ( ) Nothing inside. I have verified everything else is working by changing the "_id" above to a different field such as "firstName" and passing in a first name and I get back valid data. Why does this not

Instagram's Postgres method of implementing custom Ids for Sharding is great, but I need the implementation in MySQL. So, I converted the method found at the bottom of this blog, here: http://instagram-engineering.tumblr.com/post/10853187575/sharding-ids-at-instagram MySQL Version: CREATE TRIGGER shard_insert BEFORE INSERT ON tablename FOR EACH ROW BEGIN DECLARE seq_id BIGINT; DECLARE now_millis BIGINT; DECLARE our_epoch BIGINT DEFAULT 1314220021721; DECLARE shard_id INT DEFAULT 1; SET now_millis = (SELECT UNIX_TIMESTAMP(NOW(3)) * 1000); SET seq_id = (SELECT AUTO_INCREMENT FROM information

I am using Core Data, and want to set an auto_increment ID as one of the fields which will be unique. Is it possible to set auto_increment in iOS using core data? Can anyone help me with a small example of how to implement this? Below is the code through which I am inserting records in database. In the first field "id", i want to set it as auto_increment and not manually insert it. - (NSManagedObjectContext *)managedObjectContext { NSManagedObjectContext *context = nil; id delegate = [[UIApplication sharedApplication] delegate]; if ([delegate performSelector:@selector(managedObjectContext)]) {