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  • general database modeling and django specific modeling

    - by Shreko
    I'm wondering what is the best way to model something like the following. Lets say my company sells metal bars (parameters/fields are: length, profile_type, quantity etc.) of different profiles, where profiles may be pipe(pipe_diameter, wall_thickness) or hollow_rectangle(base, height, wall_thickness), or maybe some other profile with different parameters. Lets say maximum number of profiles would be 12, each profile having between 2-5 parameters. Should everything be in a single table like table_bars: id, length, quantity, profile_type, pipe_diameter, wall_thickness, base, height, etc.) where profile type would be (pipe, rectangle etc.) or should every shape have its own table with its own parameters and in table_bars keep only id, length, quantity profile_type and profile_id) and are there any django specific issues is multiple tables are the best answer? Thanks

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  • Implementing database redundancy with sharded tables

    - by ensnare
    We're looking to implement load balancing by horizontally sharding our tables across a cluster of servers. What are some options to implement live redundancy should a server fail? Would it be effective to do (2) INSERTS instead of one ... one to the target shard, and another to a secondary shard which could be accessed should the primary shard not respond? Or is there a better way? Thanks.

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  • Tutorials for .NET database app using SQLite

    - by ChrisC
    I have some MS Access experience, and had a class on console c++ apps, now I am trying to develop my first program. It's a little C# db app. I have the db tables and columns planned and keyed into VS, but that's where I'm stuck. I'm needing C#/VS tutorials that will guide me on configuring relationships, datatyping, etc, on the db so I can get it ready for testing of the schema. The only tutorials I've been able to find either talk about general db basics (ie, not helping me with VS/C#), or about C# communications with an existing SQL db. Thank you. (In case it matters, I'm using the open source System.Data.SQLite (sqlite.phxsoftware.com) for the db. I chose it over SQL Server CE after seeing a comparison between the two. Also I wanted a server-less version of SQL because this little app will be on other people's computers and I want to to do as little support as possible.)

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  • Main pricing and support for individual client pricing (Database Architecture ideas help - Rails)

    - by slythic
    Hi all, I have a personal project I'm planning and I came to a small hurdle. I want to have an item with price that will be the default for all clients/users. However, in my business I have some clients that are grandfathered in to some special pricing. In the case of these grandfathered in cases, I'll manually plug their special price in my admin section. Then all they will see is their special pricing while the regular users/clients see the default price. What is the best and simplest way to design the back-end for this? FYI - I'll be using rails as my framework. Many thanks! -Tony

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  • Main pricing and support for custom client pricing (Database Architecture ideas help - Rails)

    - by slythic
    Hi all, I have a personal project I'm planning and I came to a small hurdle. I want to have an item with price that will be the default for all clients/users. However, in my business I have some clients that are grandfathered in to some special pricing. In the case of these grandfathered in cases, I'll manually plug their special price in my admin section. Then all they will see is their special pricing while the regular users/clients see the default price. What is the best and simplest way to design the back-end for this? FYI - I'll be using rails as my framework. Many thanks! -Tony

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  • Database warehouse design: fact tables and dimension tables

    - by morpheous
    I am building a poor man's data warehouse using a RDBMS. I have identified the key 'attributes' to be recorded as: sex (true/false) demographic classification (A, B, C etc) place of birth date of birth weight (recorded daily): The fact that is being recorded My requirements are to be able to run 'OLAP' queries that allow me to: 'slice and dice' 'drill up/down' the data and generally, be able to view the data from different perspectives After reading up on this topic area, the general consensus seems to be that this is best implemented using dimension tables rather than normalized tables. Assuming that this assertion is true (i.e. the solution is best implemented using fact and dimension tables), I would like to seek some help in the design of these tables. 'Natural' (or obvious) dimensions are: Date dimension Geographical location Which have hierarchical attributes. However, I am struggling with how to model the following fields: sex (true/false) demographic classification (A, B, C etc) The reason I am struggling with these fields is that: They have no obvious hierarchical attributes which will aid aggregation (AFAIA) - which suggest they should be in a fact table They are mostly static or very rarely change - which suggests they should be in a dimension table. Maybe the heuristic I am using above is too crude? I will give some examples on the type of analysis I would like to carryout on the data warehouse - hopefully that will clarify things further. I would like to aggregate and analyze the data by sex and demographic classification - e.g. answer questions like: How does male and female weights compare across different demographic classifications? Which demographic classification (male AND female), show the most increase in weight this quarter. etc. Can anyone clarify whether sex and demographic classification are part of the fact table, or whether they are (as I suspect) dimension tables.? Also assuming they are dimension tables, could someone elaborate on the table structures (i.e. the fields)? The 'obvious' schema: CREATE TABLE sex_type (is_male int); CREATE TABLE demographic_category (id int, name varchar(4)); may not be the correct one.

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  • database datatype size

    - by yeeen
    Just to clarify by specifying sth like VARCHAR(45) means it can take up to max 45 characters? I rmb I heard from someone a few years ago that the number in the parathesis doesn't refer to the no of characters, then the person tried to explain to me sth quite complicated which i don't understand n forgot alr. And what is the difference btn CHAR and VARCHAR? I did search ard a bit and see that CHAR gives u the max of the size of the column and it is better to use it if ur data has a fix size and use VARCHAR if ur data size varies. But if it gives u the max of the size of the column of all the data of this col, isn't it better to use it when ur data size varies? Esp if u don't know how big is ur data size gg to be. VARCHAR needs to specify the size (CHAR don't really need right?), isn't it more troublesome?

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  • EAV Database Sheme

    - by GLO
    Hello Stackoverflow comunity! I believe that my question has to do with all db guru here! Do you know the EAV DB Scheme ( http://en.wikipedia.org/wiki/Entity-attribute-value_model ) and what they say about the performing of this model. I wonder, If I break this model into smaller tables what the result is? Let's talk about it. I have a db with more that 100K records. A lot of categories and many items ( with different properties per category ) Everything is stored in a EAV. If I try to break this scheme and create for any category a unique table is something that will I have to avoid? Yes, I know that probably I'll have a lot of tables and I'll need to ALTER them if I want to add an extra field, BUT is this so wrong? I have also read that as many tables I have, the db will be populate with more files and this isn't good for any filesystem. Any suggestion? Thank you!

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  • good database design for localization

    - by rap-uvic
    Hi, I have 3 tables for localization: Locales, ResourceKeys, and Resources. Resources is a many to many table between ResourceKeys and Locales, and stores Resource values for each resource key in multiple languages. Now if I have a table called Event, which needs a localized title and description, how do I best do this? Do I create foreign key columns in Event table which point to ResourceKey IDs each for title and description, or is there a better way?

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  • EF4 cross database relationships

    - by Daniel
    Hello all, I was wondering if EF4 support cross-databse relationships? For instance: db1 Author Id Name db2 Posts Id Content db1.Author.Id What ideally I need to do to get this relation in my ef4 model? Do you guys have any idea? Thanks

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  • c# reading integer fields from database, returning empty string when reading integer type field

    - by arnoldino
    what is wrong with this code? field="id"; table="MInvMonth"; condition="machine_id=37"; public static String getConditionedField(String field, String table, String condition) try { if (cmd == null) getConnection(); cmd.CommandText = "Select " + field + " from " + table + " where " + condition; SQLiteDataReader reader = cmd.ExecuteReader(); if (reader.HasRows==true) { reader.Read(); string s = reader[0].ToString(); // return first element reader.Close(); return s; } reader.Close(); return null; } catch (Exception e) { MessageBox.Show("Caught exception: " + e.Message+"|"+cmd.CommandText); return null; } I checked the sql statement, it turns the right value. why can't I read it? the returnvalue is "".

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  • What relational database innovations have there been in the last 10 years

    - by Simon Munro
    The SQL implementation of relational databases has been around in their current form for something like 25 years (since System R and Ingres). Even the main (loosely adhered to) standard is ANSI-92 (although there were later updates) is a good 15 years old. What innovations can you think of with SQL based databases in the last ten years or so. I am specifically excluding OLAP, Columnar and other non-relational (or at least non SQL) innovations. I also want to exclude 'application server' type features and bundling (like reporting tools) Although the basic approach has remained fairly static, I can think of: Availability Ability to handle larger sets of data Ease of maintenance and configuration Support for more advanced data types (blob, xml, unicode etc) Any others that you can think of?

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  • Source Controlled Database Data import strategies.

    - by H. Abraham Chavez
    So I've gotten a project and got the db team sold on source control for the db (weird right?) anyway, the db already exists, it is massive, and the application is very dependent on the data. The developers need up to three different flavors of the data to work against when writing SPROCs and so on. Obviously I could script out data inserts. But my question is what tools or strategies do you use to build a db from source control and populate it with multiple large sets of data?

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  • browse data in Android SQLite Database

    - by Justin C
    Is there a way for an Android user to browse the SQLite databases on his/her phone and view the data in the databases? I use the SoftTrace beta program a lot. It's great but has no way that I can find to download the data it tracks to a PC. Thanks

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  • Database warehoue design: fact tables and dimension tables

    - by morpheous
    I am building a poor man's data warehouse using a RDBMS. I have identified the key 'attributes' to be recorded as: sex (true/false) demographic classification (A, B, C etc) place of birth date of birth weight (recorded daily): The fact that is being recorded My requirements are to be able to run 'OLAP' queries that allow me to: 'slice and dice' 'drill up/down' the data and generally, be able to view the data from different perspectives After reading up on this topic area, the general consensus seems to be that this is best implemented using dimension tables rather than normalized tables. Assuming that this assertion is true (i.e. the solution is best implemented using fact and dimension tables), I would like to see some help in the design of these tables. 'Natural' (or obvious) dimensions are: Date dimension Geographical location Which have hierarchical attributes. However, I am struggling with how to model the following fields: sex (true/false) demographic classification (A, B, C etc) The reason I am struggling with these fields is that: They have no obvious hierarchical attributes which will aid aggregation (AFAIA) - which suggest they should be in a fact table They are mostly static or very rarely change - which suggests they should be in a dimension table. Maybe the heuristic I am using above is too crude? I will give some examples on the type of analysis I would like to carryout on the data warehouse - hopefully that will clarify things further. I would like to aggregate and analyze the data by sex and demographic classification - e.g. answer questions like: How does male and female weights compare across different demographic classifications? Which demographic classification (male AND female), show the most increase in weight this quarter. etc. Can anyone clarify whether sex and demographic classification are part of the fact table, or whether they are (as I suspect) dimension tables.? Also assuming they are dimension tables, could someone elaborate on the table structures (i.e. the fields)? The 'obvious' schema: CREATE TABLE sex_type (is_male int); CREATE TABLE demographic_category (id int, name varchar(4)); may not be the correct one.

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  • Database best practices

    - by user270797
    I have a table which stores comments, the comment can either come from another user, or another profile which are separate entities in this app. My original thinking was that the table would have both user_id and profile_id fields, so if a user submits a comment, it gives the user_id leaves the profile_id blank is this right, wrong, is there a better way?

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  • Auto Reconnect of Database Connection

    - by wesley
    I have a DBCP connection pool in Tomcat. The problem is that when the connection is lost briefly the appliction is broken because DBCP won't try to reconnect again later when there is a connection. Can I get DBCP to reconnect automatically?

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  • mysql database normalization question

    - by Chocho
    here is my 3 tables: table 1 -- stores user information and it has unique data table 2 -- stores place category such as, toronto, ny, london, etc hence this is is also unique table 3 -- has duplicate information. it stores all the places a user have been. the 3 tables are linked or joined by these ids: table 1 has an "table1_id" table 2 has an "table2_id" and "place_name" table 3 has an "table3_id", "table1_id", "place_name" i have an interface where an admin sees all users. beside a user is "edit" button. clicking on that edit button allows you to edit a specific user in a form fields which has a multiple drop down box for "places". if an admin edits a user and add 1 "places" for the user, i insert that information using php. if the admin decides to deselect that 1 "places" do i delete it or mark it as on and off? how about if the admin decides to select 2 "places" for the user; change the first "places" and add an additional "places". will my table just keep growing and will i have just redundant information? thanks.

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  • VS2008 adding SQL Server Database (SQL Server 2008 Mgmt Studio) not working

    - by Kahn
    I'm trying to practice using the ASP.Net MVC at home, but I ran into an impossible problem. I cannot open a connection to SQL Server 2008, I get this error: "Connections to SQL Server files (*.mdf) require SQL Server Express 2005 to function properly. ..." I've googled around for numerous responses, none of them either working or addressing this issue. I'm running Vista 32bit, my SQL Server 2008 Mgmt Studio is also 32bit, I have SP1 installed both on VS2008 Professional, as well as the SQL Server. I changed the machine.config connectionStrings from ./SQLExpress to my SQL Server 2008 name. Now if I connect manually through web.config, in an asp:datasource or code-behind, everything works fine. But for some reason trying to add a DB Connection directly like this always gets the error. This is pretty fatal, since I can't rightly do much unless I can use LINQ to SQL with my MVC test project, and this is the only way I know how. Worked fine in school and work, but not at home. Installing SQL Server Express 2005, as some have suggested, is not an option. Obviously it HAS to work with SQL Server 2008. Thanks in advance.

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  • Reverse engineer an ORM

    - by Oren Mazor
    Given a [mysql] database with a given schema, is it possible to generate an ORM interface for it? doesn't matter if its php, python or perl. in other words, I have a database and I have to ask it a few questions. while I could just craft a bunch of SQL queries (okay, several dozen), this is way more interesting to think about. is this a valid question, even? I have no design background with ORMs, but I've used a few (django's, symfony's, etc).

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  • Getting-started: Setup Database for Node.js

    - by Emile Petrone
    I am new to node.js but am excited to try it out. I am using Express as a web framework, and Jade as a template engine. Both were easy to get setup following this tutorial from Node Camp. However the one problem I am finding is I can't find a simple tutorial for getting a DB set up. I am trying to build a basic chat application (store session and message). Does anyone know of a good tutorial? This other SO post talks about dbs to use- but as this is very different from the Django/MySQL world I've been in, I want to make sure I understand what is going on. Thanks!

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