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  • ROO: how to create composit primary key in Entity

    - by Paul
    Hi, What can I do if I need to create entity for a table in production DB (Oracle 10g) with composite primary key. For example: [CODE] CREATE TABLE TACCOUNT ( BRANCHID NUMBER(3) NOT NULL, ACC VARCHAR2(18 BYTE) NOT NULL, DATE_OPEN DATE NOT NULL, DATE_CLOSE DATE, NOTE VARCHAR2(38 BYTE) ); CREATE UNIQUE INDEX PK_TACCOUNT ON TACCOUNT (BRANCHID, ACC); I don't want to change the structure of this table. Is it possible to create an "id" field using roo commands? I use Spring Roo 1.0.2.RELEASE [rev 638] Paul

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  • Django BigInteger auto-increment field as primary key?

    - by Alex Letoosh
    Hi all, I'm currently building a project which involves a lot of collective intelligence. Every user visiting the web site gets created a unique profile and their data is later used to calculate best matches for themselves and other users. By default, Django creates an INT(11) id field to handle models primary keys. I'm concerned with this being overflown very quickly (i.e. ~2.4b devices visiting the page without prior cookie set up). How can I change it to be represented as BIGINT in MySQL and long() inside Django itself? I've found I could do the following (http://docs.djangoproject.com/en/dev/ref/models/fields/#bigintegerfield): class MyProfile(models.Model): id = BigIntegerField(primary_key=True) But is there a way to make it autoincrement, like usual id fields? Additionally, can I make it unsigned so that I get more space to fill in? Thanks!

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  • Using Spring's KeyHolder with programmatically-generated primary keys

    - by smayers81
    Hello, I am using Spring's NamedParameterJdbcTemplate to perform an insert into a table. The table uses a NEXTVAL on a sequence to obtain the primary key. I then want this generated ID to be passed back to me. I am using Spring's KeyHolder implementation like this: KeyHolder key = new GeneratedKeyHolder(); jdbcTemplate.update(Constants.INSERT_ORDER_STATEMENT, params, key); However, when I run this statement, I am getting: org.springframework.dao.DataRetrievalFailureException: The generated key is not of a supported numeric type. Unable to cast [oracle.sql.ROWID] to [java.lang.Number] at org.springframework.jdbc.support.GeneratedKeyHolder.getKey(GeneratedKeyHolder.java:73) Any ideas what I am missing?

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  • Generate non-identity primary key

    - by MikeWyatt
    My workplace doesn't use identity columns or GUIDs for primary keys. Instead, we retrieve "next IDs" from a table as needed, and increment the value for each insert. Unfortunatly for me, LINQ-TO-SQL appears to be optimized around using identity columns. So I need to query and update the "NextId" table whenever I perform an insert. For simplicity, I do this immediately creating the new object. Since all operations between creation of the data context and the call to SubmitChanges are part of one transaction, do I need to create a separate data context for retrieving next IDs? Each time I need an ID, I need to query and update a table inside a transaction to prevent multiple apps from grabbing the same value. Is a separate data context the only way, or is there something better I could try?

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  • Future proof Primary Key design in postgresql

    - by John P
    I've always used either auto_generated or Sequences in the past for my primary keys. With the current system I'm working on there is the possibility of having to eventually partition the data which has never been a requirement in the past. Knowing that I may need to partition the data in the future, is there any advantage of using UUIDs for PKs instead of the database's built-in sequences? If so, is there a design pattern that can safely generate relatively short keys (say 6 characters instead of the usual long one e6709870-5cbc-11df-a08a-0800200c9a66)? 36^6 keys per-table is more than sufficient for any table I could imagine. I will be using the keys in URLs so conciseness is important.

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  • MySQL: Changing order of auto-incremented primary keys?

    - by Tom
    Hi, I have a table with a auto-incremented primary key: user_id. For a currently theoretical reason, I might need to change a user_id to be something else than it was when originally created through auto-incrementation. This means there's a possibility that the keys will not be in incremental order anymore: PK: 1 2 3 952 // changed key 4 5 6 7 I'm wondering whether this will cause problems, and whether MySQL reads something special to the incremental order of the keys, given that they should have come to existence in incremental order (which persists even when some rows are deleted). Assuming there are no associated foreignkey issues, or that these are under control, is there a problem with "messing with" the order of MySQL's autoincremented keys? Thank you.

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  • PHP/MYSQL Trouble Selecting by Primary Key

    - by djs22
    Hi all, So I have a primary key column called key. I'm trying to select the row with key = 1 via this code: $query ="SELECT * FROM Bowlers WHERE key = '1'"; $result = mysql_query($query) or die(mysql_error()); For some reason, I'm getting this result: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'key = '1'' at line 1 The mysql statement works for using other keys, ie WHERE name = 'djs22'. Any ideas?

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  • Multiple foreign keys from one table linking to single primary key in second table

    - by croker10
    Hi all, I have a database with three tables, a household table, an adults table and a users table. The Household table contains two foreign keys, iAdult1ID and iAdult2ID. The Users table has a iUserID primary key and the Adult table has a corresponding iUserID foreign key. One of the columns in the Users table is strUsername, an e-mail address. I am trying to write a query that will allow me to search for an e-mail address for either adult that has a relation to the household. So I have two questions, assuming that all the values are not null, how can I do this? And two, in reality, iAdult2ID can be null, is it still possible to write a query to do this? Thanks for your help. Let me know if you need any more information.

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  • Multiple Foriegn Keys from One Table linking to single Primary Key in second Table

    - by croker10
    Hi all, I have a database with three tables, a household table, an adults table and a users table. The Household table contains two foreign keys, iAdult1ID and iAdult2ID. The Users table has a iUserID primary key and the Adult table has a corresponding iUserID foreign key. One of the columns in the Users table is strUsername, an e-mail address. I am trying to write a query that will allow me to search for an e-mail address for either adult that has a relation to the household. So I have two questions, assuming that all the values are not null, how can I do this? And two, in reality, iAdult2ID can be null, is it still possible to write a query to do this? Thanks for your help. Let me know if you need any more information.

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  • Violation of primary key constraint, multiple users

    - by MC.
    Lets say UserA and UserB both have an application open and are working with the same type of data. UserA inserts a record into the table with value 10 (PrimaryKey='A'), UserB does not currently see the value UserA entered and attempts to insert a new value of 20 (PrimaryKey='A'). What I wanted in this situation was a DBConcurrencyException, but instead what I have is a primary key violation. I understand why, but I have no idea how to resolve this. What is a good practice to deal with such a circumstance? I do not want to merge before updating the database because I want an error to inform the user that multiple users updated this data.

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  • JPA 2.0 Eclipse Link ... Composite primary keys

    - by Parhs
    I have two entities(actually more but it doenst matter) Exam and Exam_Normals Its a oneToMany relationship... The problem is that i need a primary key for Exams_Normals PK (Exam_ID Item) Item should be 1 2 3 4 5 etc.... But cant achieve it getting errors An alternative would be to: I cound use an IDENTITY and a ManyToOne relationship at Exam_Normals but that should be like PK(Exam_Normals_ID) and a reference to Exam and an extra collumn Item to keep an order.. SO 3 collumns But to avoid the alternative tried I tried with @IdClass and got errors Tried @EmbeddedID everything nothing works Any idea??

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  • Delete duplicate records from a SQL table without a primary key

    - by Shyju
    I have the below table with the below records in it create table employee ( EmpId number, EmpName varchar2(10), EmpSSN varchar2(11) ); insert into employee values(1, 'Jack', '555-55-5555'); insert into employee values (2, 'Joe', '555-56-5555'); insert into employee values (3, 'Fred', '555-57-5555'); insert into employee values (4, 'Mike', '555-58-5555'); insert into employee values (5, 'Cathy', '555-59-5555'); insert into employee values (6, 'Lisa', '555-70-5555'); insert into employee values (1, 'Jack', '555-55-5555'); insert into employee values (4, 'Mike', '555-58-5555'); insert into employee values (5, 'Cathy', '555-59-5555'); insert into employee values (6 ,'Lisa', '555-70-5555'); insert into employee values (5, 'Cathy', '555-59-5555'); insert into employee values (6, 'Lisa', '555-70-5555'); I dont have any primary key in this table .But i have the above records in my table already. I want to remove the duplicate records which has the same value in EmpId and EmpSSN fields. Ex : Emp id 5 Can any one help me to frame a query to delete those duplicate records Thanks in advance

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  • Primary Key Identity Value Increments On Unique Key Constraint Violation

    - by Jed
    I have a SqlServer 2008 table which has a Primary Key (IsIdentity=Yes) and three other fields that make up a Unique Key constraint. In addition I have a store procedure that inserts a record into the table and I call the sproc via C# using a SqlConnection object. The C# sproc call works fine, however I have noticed interesting results when the C# sproc call violates the Unique Key constraint.... When the sproc call violates the Unique Key constraint, a SqlException is thrown - which is no surprise and cool. However, I notice that the next record that is successfully added to the table has a PK value that is not exactly one more than the previous record - For example: Say the table has five records where the PK values are 1,2,3,4, and 5. The sproc attempts to insert a sixth record, but the Unique Key constraint is violated and, so, the sixth record is not inserted. Then the sproc attempts to insert another record and this time it is successful. - This new record is given a PK value of 7 instead of 6. Is this normal behavior? If so, can you give me a reason why this is so? (If a record fails to insert, why is the PK index incremented?) If this is not normal behavior, can you give me any hints as to why I am seeing these symptoms?

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  • what's the performance difference between int and varchar for primary keys

    - by user568576
    I need to create a primary key scheme for a system that will need peer to peer replication. So I'm planning to combine a unique system ID and a sequential number in some way to come up with unique ID's. I want to make sure I'll never run out of ID's, so I'm thinking about using a varchar field, since I could always add another character if I start running out. But I've read that integers are better optimized for this. So I have some questions... 1) Are integers really better optimized? And if they are, how much of a performance difference is there between varchars and integers? I'm going to use firebird for now. But I may switch later. Or possibly support multiple db's. So I'm looking for generalizations, if that's possible. 2) If integers are significantly better optimized, why is that? And is it likely that varchars will catch up in the future, so eventually it won't matter anyway? My varchar keys won't have any meaning, except for the unique system ID part. But I may want to obscure that somehow. Also, I plan to efficiently use all the bits of each character. I don't, for example, plan to code the integer 123 as the character string "123". So I don't think varchars will require more space than integers.

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  • SQL SERVER – Create Primary Key with Specific Name when Creating Table

    - by pinaldave
    It is interesting how sometimes the documentation of simple concepts is not available online. I had received email from one of the reader where he has asked how to create Primary key with a specific name when creating the table itself. He said, he knows the method where he can create the table and then apply the primary key with specific name. The attached code was as follows: CREATE TABLE [dbo].[TestTable]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL) GO ALTER TABLE [dbo].[TestTable] ADD  CONSTRAINT [PK_TestTable] PRIMARY KEY CLUSTERED ([ID] ASC) GO He wanted to know if we can create Primary Key as part of the table name as well, and also give it a name at the same time. Though it would look very normal to all experienced developers, it can be still confusing to many. Here is the quick code that functions as the above code in one single statement. CREATE TABLE [dbo].[TestTable]( [ID] [int] IDENTITY(1,1) NOT NULL, [FirstName] [varchar](100) NULL CONSTRAINT [PK_TestTable] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, Readers Question, SQL, SQL Authority, SQL Constraint and Keys, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • trying to setup multiple primary partitions on ubuntu linux

    - by JohnMerlino
    I currently have ubuntu desktop installed on a harddrive. I want to partition the harddrive so that I can reserve 30 gigs for ubuntu server and 30 gigs for ubuntu desktop. The drive has 300 gigs available. Right now I am booting from dvd drive and installing ubuntu server. I selected "Guided partitioning" and created a 30 gig primary partition of Ext4 journaling filesystem, set "yes, format it" for format partition and set bootable flag to on. I intend to use this 30 gig partition to hold ubuntu server and allow me to boot from it. Now I have two other partitions. They are both set to "logical", one is currently using 285.8 gigs and is using ext4 (when I try to set bootable flag to true, it gives a warning "You are trying to set the bootable flag on a logical partition. The bootable flag is only useful on the primary partitions"). More alarming it says "No existing file system was detected in this partition". Actually, Im thinking that this is the parittion that is supposed to be holding my current Ubuntu Desktop. And of course I want this to be bootable and be a primary partition, so I could dual boot from this and the server partition. Now the third partition is also set to logical and it is being used as swap area. My question is regarding that second partition. Its supposed to be a primary partition thats holding my existing ubuntu desktop edition. How do I switch it to primary and to make sure that its pointing to my existing desktop installation?

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  • MySQL - What is the correct primary key method

    - by Hammerstein
    I'm starting to develop an application using MySQL and although I've developed apps before using databases, I've normally gone to the incrementing id method. The other day I was reading a posting somewhere and saw someone being picked apart for this, for not properly "normalising the database". I'm not a big database person, but I wanted to make sure I'm doing this right. Any ideas, help / guidance?

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  • Are Multi-column Primary Keys in MySQL a optimisation problem?

    - by David
    Been looking into using multi-column primary keys and as performance is extremely important with the size of traffic and database I need to know if there is anything to consider before I start throwing out the unique ID method on many of my tables and start using mulit column primary keys. So, what are the performance/optimisation pros/cons to using multi column primary keys versus a basic single column, auto-inc primary key?

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  • Resize primary partition

    - by telebog
    I have a hdd with the folowing partition table 12Gb Primary Partition (ntfs) 140Gb Extended Partition (ntfs) I want to install windows 7 and I need more space for the Primary Partition. The problem is that when I resize partitons I obtain: 12Gb Primary Partition (ntfs) 110Gb Extended Partition (ntfs) 30Gb Free Space So I can't allocate the free space to primary partition because the free space is at the end of the disk. Is there a solution to extend the primary partition as: 42Gb Primary Partition (ntfs) 110Gb Extended Partition (ntfs) without repartitioning the entire disk? I used partition magic, gparted-live-0.4.6-4 and others with no success. With the Disk Management from Vista I manage to extend primary partition, but made my partitions dinamic.

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  • Create a primary partition on Windows 7

    - by TutorialPoint
    I have windows 7 installed. On the moment i have the following partitions on 1 hard disk: (300 GB) C: (Windows) (Primary, System, Boot, Page File, Crash Dump, Active) 100 GB D: (Data) (Logical) 100 GB E: (System Reserved created after Boot repair) (primary, system) 100 MB Now i want to create a new primary partition on this disk, because i have +/- 100 GB left, for a new OS. However when trying to make a new partition, it makes it a Logical partition, not Primary. How to make it primary...?

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  • Force gdm login screen to the primary monitor

    - by Kirill
    I have two monitors attached to my video card. Primary monitor has a resolution equal to 1280x1024 and the second has 1920x1200. My gdm login screen always appears on the second monitor even if it is switched off. My question is how to force gdm to show the login screen always on the primary monitor with resolution 1280x1024? I use Nvidia GT9500 videcard in Twinview mode. I can't use Xinerama because vpdau doesn't work correclty in this mode. What I have found is that mouse pointer always appears in the center of union of the screens and center is always on the monitor with higher resolution. Login screen always shows where mouse cursor is. Now my primary monitor has a resolution equal to 1920x1080. The problem still persists, mouse cursor always appears in the right-bottom corner of the second monitor.

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  • Why not expose a primary key

    - by Angelo Neuschitzer
    In my education I have been told that it is a flawed idea to expose actual primary keys (not only DB keys, but all primary accessors) to the user. I always thought it to be a security problem (because an attacker could attempt to read stuff not their own). Now I have to check if the user is allowed to access anyway, so is there a different reason behind it? Also, as my users have to access the data anyway I will need to have a public key for the outside world somewhere in between. Now that public key has the same problems as the primary key, doesn't it?

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  • NetBeans, JSF, and MySQL Primary Keys using AUTO_INCREMENT

    - by MarkH
    I recently had the opportunity to spin up a small web application using JSF and MySQL. Having developed JSF apps with Oracle Database back-ends before and possessing some small familiarity with MySQL (sans JSF), I thought this would be a cakewalk. Things did go pretty smoothly...but there was one little "gotcha" that took more time than the few seconds it really warranted. The Problem Every DBMS has its own way of automatically generating primary keys, and each has its pros and cons. For the Oracle Database, you use a sequence and point your Java classes to it using annotations that look something like this: @GeneratedValue(strategy=GenerationType.SEQUENCE, generator="POC_ID_SEQ") @SequenceGenerator(name="POC_ID_SEQ", sequenceName="POC_ID_SEQ", allocationSize=1) Between creating the actual sequence in the database and making sure you have your annotations right (watch those typos!), it seems a bit cumbersome. But it typically "just works", without fuss. Enter MySQL. Designating an integer-based field as PRIMARY KEY and using the keyword AUTO_INCREMENT makes the same task seem much simpler. And it is, mostly. But while NetBeans cranks out a superb "first cut" for a basic JSF CRUD app, there are a couple of small things you'll need to bring to the mix in order to be able to actually (C)reate records. The (RUD) performs fine out of the gate. The Solution Omitting all design considerations and activity (!), here is the basic sequence of events I followed to create, then resolve, the JSF/MySQL "Primary Key Perfect Storm": Fire up NetBeans. Create JSF project. Create Entity Classes from Database. Create JSF Pages from Entity Classes. Test run. Try to create record and hit error. It's a simple fix, but one that was fun to find in its completeness. :-) Even though you've told it what to do for a primary key, a MySQL table requires a gentle nudge to actually generate that new key value. Two things are needed to make the magic happen. First, you need to ensure the following annotation is in place in your Java entity classes: @GeneratedValue(strategy = GenerationType.IDENTITY) All well and good, but the real key is this: in your controller class(es), you'll have a create() function that looks something like this, minus the comment line and the setId() call in bold red type:     public String create() {         try {             // Assign 0 to ID for MySQL to properly auto_increment the primary key.             current.setId(0);             getFacade().create(current);             JsfUtil.addSuccessMessage(ResourceBundle.getBundle("/Bundle").getString("CategoryCreated"));             return prepareCreate();         } catch (Exception e) {             JsfUtil.addErrorMessage(e, ResourceBundle.getBundle("/Bundle").getString("PersistenceErrorOccured"));             return null;         }     } Setting the current object's primary key attribute to zero (0) prior to saving it tells MySQL to get the next available value and assign it to that record's key field. Short and simple…but not inherently obvious if you've never used that particular combination of NetBeans/JSF/MySQL before. Hope this helps! All the best, Mark

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