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  • Natural vs surrogate keys on support tables

    - by Bugeo
    I have read many articles about the battle between natural versus surrogate primary keys. I agree in the use of surrogate keys to identify records of tables whose contents are created by the user. But in the case of supporting tables what should I use? For example, in a hypothetical table "orderStates". If you use a natural key would have the following data: TABLE ORDERSTATES {ID: "NEW", NAME: "New"} {ID: "MANAGEMENT" NAME: "Management"} {ID: "SHIPPED" NAME: "Shipped"} If I use a surrogate key would have the following data: TABLE ORDERSTATES {ID: 1 CODE: "NEW", NAME: "New"} {ID: 2 CODE: "MANAGEMENT" NAME: "Management"} {ID: 3 CODE: "SHIPPED" NAME: "Shipped"} Now let's take an example: a user enters a new order. In the case in which use natural keys, in the code I can write this: newOrder.StateOrderId = "NEW"; With the surrogate keys instead every time I have an additional step. stateOrderId_NEW = .... I retrieve the id corresponding to the recod code "NEW" newOrder.StateOrderId = stateOrderId_NEW; The same will happen every time I have to move the order in a new status. So, in this case, what are the reason to chose one key type vs the other one?

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  • Surrogate key for date dimension?

    - by Navin
    There are 2 school of thoughts : Use surrogate key preferbly in the format of YYYYMMDD as this will always be sequential. Eliminate Date dimension surrogate key and use actual date instead. My Questions to experts on dimension modeling are : 1> Which design would you prefer and why ? 2> How should we handle unknown values in each of the cases, Can we simply place NULL in Fact table for unknown dates as Foreign Key can be NULL (if no why)? 3> If we need to partition fact table on date column ,how would we achieve that in case 1. I am inclined towards using actual date and using NULL to represent UNKNOWN dates in fact table , as date related validation on fact can be done without need to look in to dimension table.

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  • How to use Data aware controls "correctly"?

    - by lyborko
    Hi, I would like to ask experienced users, if you prefer to use data aware controls to add, insert, delete and edit data in DB or you favor to do it manualy. I developed some DB applications, in which for the sake of "user friendly policy" I run into complicated web of table events (afterinsert, afteredit, after... and beforeedit, beforeinsert, before...). After that it was a quite nasty work to debug the application. Aware of this risk (later by another application) I tried to avoid this problem, so I paid increased attention to write code well, readable and comprehensive. It seemed everything all right from the beginning, but as I needed to handle some preprocessing stuff before sending and loading data etc, I run into the same problems again, "slowly and inevitably". Sometime I could not use dataaware controls anyway, and what seemed to be a "cool" feature of DAControl at the beginning it turned to an obstacle on the end. I "had to" write special routine for non-dataaware controls, in order to behave as dataaware. Then I asked myself, why on earth should I use dataaware controls? Is it better to found application architecture on non-dataaware controls? It requires more time to write bug-proof code, of course, but does it worth of it? I do not know... I happened to me several times, like jinxed : paradise on the beginning hell on the end... I do not know, if I use wrong method to write DB program, if there is some standard common practice how to proceed. Or if it is common problem to everybody? Thanx for advices and your experiences

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  • SQL efficiency argument, add a column or solvable by query?

    - by theTurk
    I am a recent college graduate and a new hire for software development. Things have been a little slow lately so I was given a db task. My db skills are limited to pet projects with Rails and Django. So, I was a little surprised with my latest task. I have been asked by my manager to subclass Person with a 'Parent' table and add a reference to their custodian in the Person table. This is to facilitate going from Parent to Form when the custodian, not the Parent, is the FormContact. Here is a simplified, mock structure of a sql-db I am working with. I would have drawn the relationship tables if I had access to Visio. We have a table 'Person' and we have a table 'Form'. There is a table, 'FormContact', that relates a Person to a Form, not all Persons are related to a Form. There is a relationship table for Person to Person relationships (Employer, Parent, etc.) I've asked, "Why this couldn't be handled by a query?" Response, Inefficient. (Really!?!) So, I ask, "Why not have a reference to the Form? That would be more efficient since you wouldn't be querying the FormContacts table with the reference from child/custodian." Response, this would essentially make the Parent is a FormContact. (Fair enough.) I went ahead an wrote a query to get from non-FormContact Parent to Form, and tested on the production server. The response time was instantaneous. *SOME_VALUE* is the Parent's fk ID. SELECT FormID FROM FormContact WHERE FormContact.ContactID IN (SELECT SourceContactID FROM ContactRelationship WHERE (ContactRelationship.RelatedContactID = *SOME_VALUE*) AND (ContactRelationship.Relationship = 'Parent')); If I am right, "This is an unnecessary change." What should I do, defend my position or should I concede to the managers request? If I am wrong. What is my error? Is there a better solution than the manager's?

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  • Need some serious help with self join issue.

    - by kralco626
    Well as you may know, you cannot index a view with a self join. Well actually even two joins of the same table, even if it's not technically a self join. A couple of guys from microsoft came up with a work around. But it's so complicated I don't understand it!!! The solution to the problem is here: http://jmkehayias.blogspot.com/2008/12/creating-indexed-view-with-self-join.html The view I want to apply this work around to is: create VIEW vw_lookup_test WITH SCHEMABINDING AS select count_big(*) as [count_all], awc_txt, city_nm, str_nm, stru_no, o.circt_cstdn_nm [owner], t.circt_cstdn_nm [tech], dvc.circt_nm, data_orgtn_yr from ((dbo.dvc join dbo.circt on dvc.circt_nm = circt.circt_nm) join dbo.circt_cstdn o on circt.circt_cstdn_user_id = o.circt_cstdn_user_id) join dbo.circt_cstdn t on dvc.circt_cstdn_user_id = t.circt_cstdn_user_id group by awc_txt, city_nm, str_nm, stru_no, o.circt_cstdn_nm, t.circt_cstdn_nm, dvc.circt_nm, data_orgtn_yr go Any help would be greatly apreciated!!! Thanks so much in advance!

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  • MySQL - query to return CSV in a field?

    - by StackOverflowNewbie
    Assume I have the following tables: TABLE: foo - foo_id (PK) TABLE: tag - tag_id (PK) - name TABLE: foo_tag - foo_tag_id (PK) - foo_id (FK) - tag_id (FK) How do I query this so that I get a result like this: ========================== | foo_id | tags | ========================== | 1 | foo, bar | | 2 | foo | | 3 | bar | -------------------------- Basically, I need all of foo's tags in one column, comma separated. Possible in MySQL?

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  • Solr; "rookie" question

    - by Camran
    I have a SolrPhpClient on my classifieds website, and whenever users wants to add/remove classified the index in Solr gets updated via Php code. So I wonder, does this mean that my Solr index is open for anybody to alter with? Same Q applies to the Solr Admin page. If I set a password for the admin page, does this mean that my classifieds website wont have access to updating/removing documents from the Solr index? Thanks

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  • Back Orders for ERP: data model references ?

    - by Patrick Honorez
    I have built an ERP using Sql Server as a back-end. These are the different types of Client documents (there are also Supplier Docs): Order -- impact: BO Delivery Note (also used for returns, with negative quantity) --impact: BO, Stock Invoice --impact: accounting only Credit Note --impact: accounting, BO I use a complex system of self joins (at detail level) to find out the quantities in each OrderDetail that still have a backorder (BO). It'd like to simplify this using a [group] field that could be used through all detail line related to an original order. There are many difficult things to trace: a Return of a product may be due to a defect and thus increase the BO, or it can be just a return, joined with a Credit Note, and then has no impact on BO. My question is: do you know of any real good reference (book, web) for this matter ?

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  • Firebird multiple statements

    - by Aldo
    Hello, is there any way to execute multiple statements (none of which will have to return anything) on Firebird? Like importing a SQL file and executing it. I've been looking for a while and couldn't find anything for this.

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  • Prevent "hg status" from showing everything under untracked directories

    - by Wei Hu
    I find the output of hg status too verbose for untracked directories. Suppose I have an empty repository that's managed by both git and hg. So there would be two directories, .git and .hg. The output of git status is: # Untracked files: # (use "git add <file>..." to include in what will be committed) # # .hg/ The output of hg status is: ? .git/HEAD ? .git/config ? .git/description ? .git/hooks/applypatch-msg.sample ? .git/hooks/commit-msg.sample ? .git/hooks/post-commit.sample ? .git/hooks/post-receive.sample ? .git/hooks/post-update.sample ? .git/hooks/pre-applypatch.sample ? .git/hooks/pre-commit.sample ? .git/hooks/pre-rebase.sample ? .git/hooks/prepare-commit-msg.sample ? .git/hooks/update.sample ? .git/info/exclude Is there a way to reduce its output to something like the following line? ? .git/

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  • Foreign Key Relationships and "belongs to many"

    - by jan
    I have the following model: S belongs to T T has many S A,B,C,D,E (etc) have 1 T each, so the T should belong to each of A,B,C,D,E (etc) At first I set up my foreign keys so that in A, fk_a_t would be the foreign key on A.t to T(id), in B it'd be fk_b_t, etc. Everything looks fine in my UML (using MySQLWorkBench), but generating the yii models results in it thinking that T has many A,B,C,D (etc) which to me is the reverse. It sounds to me like either I need to have A_T, B_T, C_T (etc) tables, but this would be a pain as there are a lot of tables that have this relationship. I've also googled that the better way to do this would be some sort of behavior, such that A,B,C,D (etc) can behave as a T, but I'm not clear on exactly how to do this (I will continue to google more on this) What do you think is the better solution? UML: Here's the DDL (auto generated). Just pretend that there is more than 3 tables referencing T. -- ----------------------------------------------------- -- Table `mydb`.`T` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`T` ( `id` INT NOT NULL AUTO_INCREMENT , PRIMARY KEY (`id`) ) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`S` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`S` ( `id` INT NOT NULL AUTO_INCREMENT , `thing` VARCHAR(45) NULL , `t` INT NOT NULL , PRIMARY KEY (`id`) , INDEX `fk_S_T` (`id` ASC) , CONSTRAINT `fk_S_T` FOREIGN KEY (`id` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`A` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`A` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff` VARCHAR(45) NULL , `bar` VARCHAR(45) NULL , `foo` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`B` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`B` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff2` VARCHAR(45) NULL , `foobar` VARCHAR(45) NULL , `other` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB; -- ----------------------------------------------------- -- Table `mydb`.`C` -- ----------------------------------------------------- CREATE TABLE IF NOT EXISTS `mydb`.`C` ( `id` INT NOT NULL AUTO_INCREMENT , `T` INT NOT NULL , `stuff3` VARCHAR(45) NULL , `foobar2` VARCHAR(45) NULL , `other4` VARCHAR(45) NULL , PRIMARY KEY (`id`) , INDEX `fk_A_T` (`T` ASC) , CONSTRAINT `fk_A_T` FOREIGN KEY (`T` ) REFERENCES `mydb`.`T` (`id` ) ON DELETE NO ACTION ON UPDATE NO ACTION) ENGINE = InnoDB;

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  • Are there any examples/tutorials of using Spring 3.0 with Cassandra as a backend?

    - by zeroDivisible
    Hello, As I had written in title, I am trying to learn Spring 3.0 (I already know Django, Pylons and few simpler MVC frameworks) and try to use Cassandra as a backend for my web application. Are there any real world examples of doing this? Or maybe some tutorials? I know about the existence of documentation of both technologies, yet I am looking for something "faster" to read and get me rolling.

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  • Best practices for handling unique constraint violation

    - by umesh awasthi
    Hi All, While working in my application i came across a situation in which there are likely chances to Unque Constraints Violation.I have following options Catch the exception and throw it back to UI At UI check for the exception and show approrpriate Error Message This is something different idea is to Check in advance about the existance of the given Unique value before starting the whole operation. My Question is what might be the best practice to handle such situation.Currently we are using combo of Struts2+Spring 3.x+Hibernate 3.x Thanks in advance

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  • How can I execute a SQL query in emacs lisp?

    - by Chris R
    I want to execute an SQL query and get its result in elisp: (let ((results (do-sql-query "SELECT * FROM a_table"))) (do-something-with results)) I'm using Postgres, and I already know all of my connection information (host, username, password, db et al) I just want to execute the query and get the result back, synchronously.

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  • DB design abbreviations

    - by CChriss
    I know PK means primary key and FK means foreign key, but what do "rK" (in section 3) and "PF" (in sections 3, 4, 6, 7, and 8) mean on this page? http://www.databaseanswers.org/tutorial4_data_modelling/index.htm And what does "FF" mean (in the Customer_Addresses table) on this page? -I'm new so it would only let me put in one hyperlink, so copy/paste this to go to the page I'm asking about: databaseanswers.org/tutorial4_db_schema/tutorial_slide_7.htm Thanks. Edit: also, I understand the concepts of primary keys and foreign keys, but what are these other ones used for?

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  • Designing a Tag table that tells how many times it's used

    - by Satoru.Logic
    Hi, all. I am trying to design a tagging system with a model like this: Tag: content = CharField creator = ForeignKey used = IntergerField It is a many-to-many relationship between tags and what's been tagged. Everytime I insert a record into the assotication table, Tag.used is incremented by one, and decremented by one in case of deletion. Tag.used is maintained because I want to speed up answering the question 'How many times this tag is used?'. However, this seems to slow insertion down obviously. Please tell me how to improve this design. Thanks in advance.

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  • SQL Design: representing a default value with overrides?

    - by Mark Harrison
    I need a sparse table which contains a set of "override" values for another table. I also need to specify the default value for the items overridden. For example, if the default value is 17, then foo,bar,baz will have the values 17,21,17: table "things" table "xvalue" name stuff name xval ---- ----- ---- ---- foo ... bar 21 bar ... baz ... If I don't care about a FK from xvalue.name - things.name, I could simply put a "DEFAULT" name: table "xvalue" name xval ---- ---- DEFAULT 17 bar 21 But I like having a FK. I could have a separate default table, but it seems odd to have 2x the number of tables. table "xvalue_default" xval ---- 17 table "xvalue" name xval ---- ---- bar 21 I could have a "defaults table" tablename attributename defaultvalue xvalue xval 17 but then I run into type issues on defaultvalue. My operations guys prefer as compact a representation as possible, so they can most easily see the "diff" or deviations from the default. What's the best way to represent this, including the default value? This will be for Oracle 10.2 if that makes a difference.

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  • Alternative design for a synonyms table?

    - by Majid
    I am working on an app which is to suggest alternative words/phrases for input text. I have doubts about what might be a good design for the synonyms table. Design considerations: number of synonyms is variable, i.e. football has one synonym (soccer), but in particular has two (particularly, specifically) if football is a synonym to soccer, the relation exists in the opposite direction as well. our goal is to query a word and find its synonyms we want to keep the table small and make adding new words easy What comes to my mind is a two column design with col a = word and col b = delimited list of synonyms Is there any better alternative? What about using two tables, one for words and the other for relations?

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  • Many-To-Many dimensional model

    - by Mevdiven
    Folks, I have a dimension table called DIM_FILE which holds information of the files we received from customers. Each file has detail records which constitutes my FACT table, CUST_DETAIL. In the main process, file is gone through several stages and each stage tags a status to it. Long in a short, I have many-to-many relationship. Any ideas around star schema dimensional modeling. A customer record only belong to a single file and a file can have multiple statuses. FACT ---- CustID FileID AmountDue DIM_FILE -------- FileID FileName DateReceived FILE_STATUS ----------- FileID StatusDateTime StatusCode

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