auto-increment

问题 I have a table with items in it (id, name, etc) and I want some kind of database scheme to be able to have multiple copies of the item while still being able to increment the ids. There will be a field called startdate or date_from_which_this_entry_should_be_used. I've thought of two ways of implementing this: Have a table with only ids (primary key, auto-increment) and do joins to a table that has all the item information. Advantages: easy to understand hard for someone that comes after me

问题 So this is more of a query of how one might go about doing this, I'm new to MySQL/PHP coding when it comes to more than the basics so I'm just wondering how one might set up an auto incrementing int where if two lastnames were the same it would count them. I was unable to find anything on it while searching online but an example would be: in the database we have 5 users 1. james smith 1 2. terry smith 2 3. john smith 3 4. jerry fields 1 5. tom straus 1 When these users register I need an int

问题 Heres my problem. I have an autoincrement primary key in sql table lets say table look like this ID | Name| 1 John 2 Jack 3 Bill 4 Joe Then i delete row 2 Jack ID | Name| 1 John 3 Bill 4 Joe And what I want to achieve is to change id column so the table will look like this ID | Name| 1 John 2 Bill 3 Joe Is there a way to do it ? thanks in advance 回答1: I will never do that but you can: create a new autoincrement primary key named ID2 delete ID column rename ID2 column as ID 回答2: Set identity

问题 I've found a problem with Hibernate and composite key with one of its column auto incremented. I'm using MySQL and primary key composed of 2 columns, GID and LANG. GID column is set as AUTO_INCREMENT. Insert is working, hibernate inserts new row, MySQL adds auto_generated id when GID is null. However, Hibernate doesn't set the GID field in object given to persist. I've heard of problems generally connected with using composite primary key with hibernate, so I'm asking if this is a bug in

问题 I've found a problem with Hibernate and composite key with one of its column auto incremented. I'm using MySQL and primary key composed of 2 columns, GID and LANG. GID column is set as AUTO_INCREMENT. Insert is working, hibernate inserts new row, MySQL adds auto_generated id when GID is null. However, Hibernate doesn't set the GID field in object given to persist. I've heard of problems generally connected with using composite primary key with hibernate, so I'm asking if this is a bug in

问题 This question already has an answer here : Don't use deleted primary keys (1 answer) Closed 3 years ago . I have a SQLite table, with a few columns, including an "ID" column which is INTEGER PRIMARY KEY. When I insert, this value increments as expected. However, when I delete all rows, this column's value reverts to 1 on the next insert. Is there a way to have the column value continue to increment from the highest value before deletion? For example: (empty table) insert insert (ID value of

问题 Mysql autoincrmenting is not sequential. when i was trying to upload csv bulk data it's skipping some of the auto increment id The auto increment id is not sequential The db engine is innodb & id is auto increment example id color 1 red 2 blue 3 green 4 orange 9 pink 10 white 11 black 16 gray 17 brown The id is not sequential. 回答1: don't know about codeignitor and specifics of transactions, but i do know that "catched fails" in queries (like insert ignore ) have the effect of NOT inserting,

问题 Mysql autoincrmenting is not sequential. when i was trying to upload csv bulk data it's skipping some of the auto increment id The auto increment id is not sequential The db engine is innodb & id is auto increment example id color 1 red 2 blue 3 green 4 orange 9 pink 10 white 11 black 16 gray 17 brown The id is not sequential. 回答1: don't know about codeignitor and specifics of transactions, but i do know that "catched fails" in queries (like insert ignore ) have the effect of NOT inserting,

问题 Mysql autoincrmenting is not sequential. when i was trying to upload csv bulk data it's skipping some of the auto increment id The auto increment id is not sequential The db engine is innodb & id is auto increment example id color 1 red 2 blue 3 green 4 orange 9 pink 10 white 11 black 16 gray 17 brown The id is not sequential. 回答1: don't know about codeignitor and specifics of transactions, but i do know that "catched fails" in queries (like insert ignore ) have the effect of NOT inserting,

问题 I'm facing some performance issues while trying to connect Hibernate with SAP HANA In-Memory database, which has no support for AUTO_INCREMENT (http://scn.sap.com/thread/3238906). So I have set Hibernate to use sequences for ID generation. @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="myseq") @SequenceGenerator(name="myseq",sequenceName="MY_SEQ",allocationSize=1) But when I insert big number of records (e.g., 40000), Hibernate first generates IDs. It looks like: DEBUG Thread-1