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  • How to design model for multi-tiered data?

    - by Chris
    Say I have three types of object: Area, Subarea and Topic. I want to be able to display an Area, which is just a list of Subareas and the Topics contained in those Subareas. I never want to be able to display Subareas separately - they're just for breaking up the Topics. Topics can, however, appear in multiple Areas (but probably under the same Subarea). How would I design a model for this? I could use ForeignKey from Topic to Subarea and from Subarea to Area, but it seems unnecessarily complex given that I never want to interact with subareas themselves. Also, none of these objects are ever altered or added to by the user. They're just for me to represent information. Maybe there is a better way to represent it all?

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  • Three-way full outer join in SQLite

    - by Vince
    I have three tables with a common key field, and I need to join them on this key. Given SQLite doesn't have full outer or right joins, I've used the full outer join without right join technique on Wikipedia with much success. But I'm curious, how would one use this technique to join three tables by a common key? What are the efficiency impacts of this (the current query takes about ten minutes)? Thanks!

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  • What is the best way to restore(rollback) data in an application to a specified state(date) ?

    - by panzerschreck
    Hello, An example would set the context right, the example below captures the various states of the entity, which needs to be reverted(rolled back) . State 1 - Recorded on 01-Mar-2010 Column1 Column2 Data1 0.56 State 2 - Recorded on 02-Mar-2010 Column1 Column2 Data1 0.57 State 3 - Recorded on 03-Mar-2010 Column1 Column2 Data1 0.58 User notices that state3 is not what he intended to be in, decides to revert back to state2. One approach that I can think of, without modifying the entity is via "auditing" all the inserts/updates, as below, the rollback information captures the data just before the updates/modifications on the entity, so that it can be applied in an order when you need to revert.Please note that changing the entity's schema, is not an option. Rollback - R1 recorded on 01-Mar-2010 Column1 Column2 Data1 0.56 Rollback - R2 Recorded on 02-Mar-2010 Column1 Column2 Data1 0.56 Rollback - R3 Recorded on 03-Mar-2010 Column1 Column2 Data1 0.57 So, to get to state2 , we would start with rollback information R1,apply R2 onto it. Is there a better approach to achieve this ? Thanks for your time.

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  • What is the differnce between an Oracle and Microsoft schema?

    - by Tarzan
    I am working on an enterprise project. Some of the team has an Oracle background and some has a Microsoft SQL Server background. There is much confusion when we talk about schemas. I am trying to provide some clarity. Is this an accurate way to describe the difference in the meaning of schemas between the two technologies? An Oracle schema is associated with a single user and consists of the objects owned by the user. A MS SQL Server schema schema is a namespace.

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  • What's the best way to test MSSQL connection programmatically?

    - by backslash17
    I need to develop a single routine that will be fired each 5 minutes to check if a list of MSSQL servers (10 to 12) are up and running. I can try to obtain a simple query in each one of the servers but this means that I have to create a table, view or stored procedure in every server, even if I use any already made SP I need to have a registered user in each server too. The servers are not in the same phisical location so having those requirements would be a complex task. Is there a way to simply "ping" from c# one MSSQL server? Thanks in advance!

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  • What will happen if I change the type of a column from int to year?

    - by MachinationX
    I have a table in MySQL 4.0 which currently has a year field as a smallint(6) type. What will happen if I convert it directly to a Year type with a query like the following: ALTER TABLE t MODIFY y YEAR(4) NOT NULL DEFAULT CURRENT_TIMESTAMP; When the current members of column y have values like 2010? I assume that because the year type is technically values from 1-255, values above that will be truncated or broken. So if MySQL isn't smart enough to realize that 2010(int) = 110(year), what would be the simplest query or queries to convert the values? Thanks for your help!

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  • Set to null a parent record so that children are removed: howto?

    - by EugeneP
    How to delete a child row (on delete cascade ?) when setting a null value on a parent? Here's the db design. table A [id, b_id_1, b_id_2] table B [id, other fields...] b_id_1 and b_id_2 can be NULL if any of them is null, it means NO B records for corresponding FK (there are 2 of them) so (b_id_1,b_id_2) can be (null,null), (100, null), (null, 100_or_any_other_number) etc How in one SQL query both set b_id_1 or b_id_2 to null and delete all rows from B that have this id? What FK design should be applied to the 2 tables? what foreign keys should be added? A - B (FK_1: A.b_id_1 references B.id, FK_2: A.b_id_2 references B.id) and also B-A (FK_3: B.id references A.b_id_1, FK_4: B.id references A.b_id_2) ? But again, setting an A's b_id_1 or A's b_id_2 to null - will it remove any of B's records? I don't think so. So how to do that?

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  • What type of data store should I use for my ios app?

    - by mwiederrecht
    I am pretty new to ios and using servers so forgive me. I am building an ios app for research. I need to monitor things that the user does and then push it up to a server for analysis (yes, with user and IRB permission). On the client's side I need to keep quite a bit of data that won't really change except in the case of pulling an updated version from the server, and then a minimal amount of user-specific data. Most of the data I will collect needs to be pushed to a server for analysis and then can be deleted from the client side. I am struggling to figure out what kind of data store I need to use, especially since I am not quite sure how the pushing and pulling from the server process works yet. Does it make sense to use Core Data? XML? SQLite? I like the Core Data idea, but I am not sure what kind of problems I will run into when I need to send large amounts of data to it and from it from the server. I imagine I might need to send data in a different form than it is probably stored in on either end - so what kind of overhead am I likely to run into in the process of converting that data? Is there a good format to save stuff in that would work well for me on both ends AND for sending the data? As you can probably tell, I could use some advice. Thanks!

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  • Is this safe? Is this OK to do in MYSQL?

    - by alex
    I have always done this: mysqldump -hlocalhost -uuser -ppass MYDATABASE > /home/f/db_backup/MYDATABASE.sql mysql -uuser -ppass MYDATABASE < MYDATABASE.sql But, if I do this instead...is this safe? Is this identical to the above??? mysqldump -hlocalhost -uuser -ppass MYDATABASE | gzip > /home/f/db_backup/MYDATABASE.sql.gz zcat MYDATABASE.sql.gz | mysql -uuser -ppass MYDATABASE

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  • FKs on all tables for status colunm

    - by Jonarch
    I have a colunm "Status" in every table in my DB. The purpose of it is to show if the given row is in use or if it has been deactivated. So values can be (0=deactive and 1= active). Two ways I see this: I can have enums or I am thinking if it is better to keep this colunm as a FK which references the main system data dictionary table which has all the codes used on the system. (website) The benefit is every table, every row can then be centralized through this FK. So if i ever want to check all rows which are deactive on my system i can from this table as all th child tables will have like status = ID 233, where 233 = deactive in the data dictionary table. Any benefit or should i stick with the old way of enums?. Also I am thinking if i need one more status for deleted or is that same as deactivated?

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  • extract transform load

    - by mitch
    Wikipedia defines a 'typical' ETL cycle as : Cycle initiation Build reference data Extract (from sources) Validate Transform (clean, apply business rules, check for data integrity, create aggregates or disaggregates) Stage (load into staging tables, if used) Audit reports (for example, on compliance with business rules. Also, in case of failure, helps to diagnose/repair) Publish (to target tables) Archive Clean up ..What is meant by 'Build reference data'?

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  • Conditional PIVOT/transform problem

    - by IanC
    Hi folks I have a table with three columns, which we'll call ID1, ID2, and Value. Sample data: ID ID1 Value 1 1 0 1 2 1 1 3 1 1 3 2 1 4 0 1 4 1 1 5 0 1 5 2 2 1 2 Value is limited to 0, 1, or 2. What I need to do is pivot/transform this data into a column-based count of how many times each possible Value appears, grouped by ID, ID1. The output of the above should be: ID ID1 Val0 Val1 Val2 1 1 1 0 0 1 2 0 2 0 1 3 0 1 1 1 4 1 1 0 1 5 1 0 1 2 1 0 0 1 I'm using SQL Server 2008. How do I do this?

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  • Has inheritance become bad?

    - by mafutrct
    Personally, I think inheritance is a great tool, that, when applied reasonably, can greatly simplify code. However, I seems to me that many modern tools dislike inheritance. Let's take a simple example: Serialize a class to XML. As soon as inheritance is involved, this can easily turn into a mess. Especially if you're trying to serialize a derived class using the base class serializer. Sure, we can work around that. Something like a KnownType attribute and stuff. Besides being an itch in your code that you have to remember to update every time you add a derived class, that fails, too, if you receive a class from outside your scope that was not known at compile time. (Okay, in some cases you can still work around that, for instance using the NetDataContract serializer in .NET. Surely a certain advancement.) In any case, the basic principle still exists: Serialization and inheritance don't mix well. Considering the huge list of programming strategies that became possible and even common in the past decade, I feel tempted to say that inheritance should be avoided in areas that relate to serialization (in particular remoting and databases). Does that make sense? Or am messing things up? How do you handle inheritance and serialization?

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  • SQL Server 2005: Rename DB Server Instance Name?

    - by Code Sherpa
    Hi, Can somebody tell me how to rename the DB server instance name and a DB name in SQL Server 2005? Right Now I Have SERVER/OLDNAME -- oldnameDB I want to change the server instance and also change the db name. I have tried: EXEC sp_renamedb 'oldName', 'newName' and that has changed the dbname as it appers in the tree directory. But, when I do "select @@servername" it is the old name. Also, the MDF and LDF files are still the old name. How do change instance and db names as a clean sweep across the server? Thanks.

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  • References/walkthroughs for maintaining database schemas with Visual Studio 2010?

    - by user206356
    I have Visual Studio 2010 Beta 2 and SQL Server 2008 installed. I'm working with a populated database and want to modify various column types. SQL Server Management Studio requires me to drop tables to do this, and get pretty finicky given my moderate level of knowledge of SQL Server. However, I heard the new database project type supports changing the database schema to the desired format and it will handle creating and running all the scripts to implement the changes. I've created a VS2010 database project using the existing database as the source, but so far haven't had much luck figuring out the appropriate method to make the changes without getting an error. As a result, I'm looking for any reference info I can find on using VS2010's capabilities in this area. Any suggestions?

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  • what is the out put?

    - by user329820
    Hi this is my code but when I run it in mysql it will show an error because of datatype but my friend checked it with sql server and it doesn't show error and also insert the value: 32769 .which of them is correct? CREATE TABLE T1 (A INTEGER NOT NULL); INSERT T1 VALUES (32768.5);

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  • how to get result from this data.

    - by Shantanu Gupta
    I want to compute result from this table. I want quantity 1 - quantity2 as another column in the table shown below. this table has more such records I am trying to query but not been able to get result. select * from v order by is_active desc, transaction_id desc PK_GUEST_ITEM_ID FK_GUEST_ID QUANTITY TRANSACTION_ID IS_ACTIVE ---------------- -------------------- ---------------------- -------------------- ----------- 12963 559 82000 795 1 12988 559 79000 794 0 12987 559 76000 793 0 12986 559 73000 792 0 12985 559 70000 791 0 12984 559 67000 790 0 12983 559 64000 789 0 12982 559 61000 788 0 12981 559 58000 787 0 12980 559 55000 786 0 12979 559 52000 785 0 12978 559 49000 784 0 12977 559 46000 783 0 12976 559 43000 782 0 I want another column that will contain the subtraction of two quantities . DESIRED RESULT SHOULD BE SOMETHING LIKE THIS PK_GUEST_ITEM_ID FK_GUEST_ID QUANTITY Result TRANSACTION_ID IS_ACTIVE ---------------- -------------------- ---------------------- -------------------- ----------- 12963 559 82000 3000 795 1 12988 559 79000 3000 794 0 12987 559 76000 3000 793 0 12986 559 73000 3000 792 0 12985 559 70000 3000 791 0 12984 559 67000 3000 790 0 12983 559 64000 3000 789 0 12982 559 61000 3000 788 0 12981 559 58000 3000 787 0 12980 559 55000 3000 786 0 12979 559 52000 3000 785 0 12978 559 49000 3000 784 0 12977 559 46000 3000 783 0 12976 559 43000 NULL 782 0

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  • Any way to make this PostgreSQL count query any faster?

    - by Ben Dauphinee
    I'm running a case-insensitive search on a table with 7.2 million rows, and I was wondering if there was any way to make this query any faster? Currently, it takes approx 11.6 seconds to execute, with just one search parameter, and I'm worried that as soon as I add more than one, this query will become massively slow. SELECT count(*) FROM "exif_parse" WHERE (description ~* 'canon')

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  • Difference between dates when grouping in SQL

    - by CeejeeB
    I have a table of purchases containing a user_id and a date_of_purchase. I need to be able to select all the users who have made 2 purchases within 12 months of each other. The dates can be any point in time as long as they are less than 12 months apart. e.g. user_id date_of_purchase 123 01/Jan/2010 124 01/Aug/2010 123 01/Feb/2010 124 05/Aug/2008 In this example i want user_id 123

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