auto-increment

问题 What is the max size of SQL Server identity field (int)? I am deleting and inserting hundereds of records at a time a few times a day in a few tables and I'm curious what effect this will have regarding the auto-identity field. I can run a job every night or so and truncate this data, if needed. I'd appreciate your thoughts. Thank you. 回答1: An INT will take you up to 2,147,483,647. A BIGINT will get you 9,223,372,036,854,775,807. 回答2: 2^31 - 1 (2,147,483,647) is the upper range of an int 回答3:

问题 Suppose the table with two columns: ParentEntityId int foreign key Number int ParentEntityId is a foreign key to another table. Number is a local identity, i.e. it is unique within single ParentEntityId . Uniqueness is easily achieved via unique key over these two columns. How to make Number be automatically incremented in the context of the ParentEntityId on insert? Addendum 1 To clarify the problem, here is an abstract. ParentEntity has multiple ChildEntity , and each ChiildEntity should

问题 I would like to create a number like: 000000000001 to save to the database. I obviously cannot increment in this fashion (I don't think) in a database, so I'm looking for the most efficient method for pulling the previous number from the database and incrementing it by 1 to create the next record: 000000000002 and so on... If I store the first number manually, can I do some sort of manual typing to make it hold its number of zeros? I don't even know where to start. 回答1: All the leading zeroes

问题 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

问题 This is what I'm trying to do: I have 2 tables... CREATE TABLE `parent` ( `id` int(11) NOT NULL AUTO_INCREMENT, `data` text, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8; CREATE TABLE `child` ( `parent_id` int(11) DEFAULT NULL, `related_ids` int(11) DEFAULT NULL, KEY `parent_id` (`parent_id`), KEY `related_ids` (`related_ids`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8; And then a constraint: ALTER TABLE `parent` ADD FOREIGN KEY (`id`) REFERENCES `child` (`parent_id`);

问题 I know this isn't so complicated but I can't remember how to do. I just need to know the next auto increment. $result = mysql_query(" SHOW TABLE STATUS LIKE Media "); $data = mysql_fetch_assoc($result); $next_increment = $data['Auto_increment']; ...but i won't work for me, what am I doing wrong? 回答1: $result = mysql_query(" SHOW TABLE STATUS LIKE 'Media' "); $data = mysql_fetch_assoc($result); $next_increment = $data['Auto_increment']; The name of the table needed to be wrapped with single

问题 ok this isn't spamming and it's supposed to be simple I don't know why it's not working this is my code: gamesdatabase = openOrCreateDatabase("GamesDatabase", MODE_PRIVATE, null); gamesdatabase.execSQL("CREATE TABLE IF NOT EXISTS Games (ID INTEGER PRIMARY KEY, Name VARACHAR, NPlayers INT(1), NRounds INT(2), WinScore INT(2));"); gamesdatabase.execSQL("INSERT INTO Games (ID, Name, NPlayers, NRounds, WinScore ) VALUES ( NULL, 'TAWLA',2,0,0 );"); gamesdatabase.execSQL("INSERT INTO Games (ID, Name

问题 Per the code below, I am getting the following message. I am fairly certain "why" I am getting it, I just don't know how to rearrange the code to move/remove/replace one of the error causing statements. "Compile with /main to specify the type that contains the entry point." There is a bunch of code in there under "static void Main(string[] args)" , that I got from http://support.microsoft.com/kb/816112 forthe purpose of getting the ID from auto-increment, so i can have it auto increment, when

问题 I want to show one custom column as alias but need to increment by using auto character. id subid dollar packetname 168 355 5813 ND-1 169 355 359 ND-1 170 356 559 ND-2 171 362 4536 ND-10 172 362 484 ND-10 134 329 4698 ND-12 135 329 435 ND-12 125 330 6293 ND-13 126 330 4293 ND-13 127 330 693 ND-13 I need a output with another updated packet. column with autoincrement character id subid dollar packetname updated packet 168 355 5813 ND-1 ND-1 169 355 359 ND-1 ND-1A 170 356 559 ND-2 ND-2 171 362

问题 I have recently started a new job and noticed that all the SQL tables use the GUID data type for the primary key. In my previous job we used integers (Auto-Increment) for the primary key and it was a lot more easier to work with in my opinion. For example, say you had two related tables; Product and ProductType - I could easily cross check the 'ProductTypeID' column of both tables for a particular row to quickly map the data in my head because its easy to store the number (2,4,45 etc) as