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  • SQL - How to display the students with the same age?

    - by Cristian
    the code I wrote only tells me how many students have the same age. I want their names too... SELECT YEAR(CURRENT DATE-DATEOFBIRTH) AS AGE, COUNT(*) AS HOWMANY FROM STUDENTS GROUP BY YEAR(CURRENT DATE-DATEOFBIRTH); this returns something like this: AGE HOWMANY --- ------- 21 3 30 5 Thank you. TABLE STUDENTS COLUMNS: StudentID (primary key), Name(varchar), Firstname(varchar), Dateofbirth(varchar) I was thinking of maybe using the code above and somewhere add the function concat that will put the stundents' names on the same row as in

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  • Referencing surrogate key

    - by Arman
    I have a table that has an autoincrement surrogate key. I want to use it as a foreign key of my other table. The thing is, I cant figure out how I can reference it to that table, because it is nearly impossible to determine what I have to reference(the actual value of the surrogate key). Please be noted that what I am trying to do is adding a tuple/record through my program(outside the dbms). The process is: Add a new record in Table1 and generate an autoincrement key. Update Add a new record in Table2 and reference its foreign key to the primary key of Table1. Update My question is : HOW do I store the foreign key if I didnt know what is it?

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  • Import CSV to class structure as the user defines

    - by Assimilater
    I have a contact manager program and I would like to offer the feature to import csv files. The problem is that different data sources order the fields in different ways. I thought of programming an interface for the user to tell it the field order and how to handle exceptions. Here is an example line in one of many possible field orders: "ID#","Name","Rank","Address1","Address2","City","State","Country","Zip","Phone#","Email","Join Date","Sponsor ID","Sponsor Name" "Z1234","Call, Anson","STU","1234 E. 6578 S.","","Somecity","TX","United States","012345","000-000-0000","[email protected]","5/24/2010","z12343","Quantum Independence" Notice that in one data field "Name" there is a comma to separate last name and first name and in another there is not. My plan is to have a line for each field (ie ID, Name, City etc.) and a statement "import to" and list box with options like: Don't Import, BusinessJoin Date, First Name, Zip and the program recognizes those as properties of an object... I'd also like the user to be able to record preset field orders so they can re-use them for csv files from the same download source. Then I also need it to check if a record all ready exists (is there a record for Anson Call all ready?) and allow the user to tell it what to do if there is a record (ie mailing address may have changes, so if that field is filled overwrite it, or this mailing address is invalid, leave the current data untouched for this person, overwrite the rest). While I'm capable of coding this...i'm not very excited about it and I'm wondering if there's a tool or set of tools out there to all ready perform most of this functionality... I hope this makes sense...

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  • question with its query

    - by user329820
    Hi this is my homework and the question is this: List the average balance of customers by city and short zip code (the first five digits of thezip code). Only include customers residing in Washington State (‘WA’). also the Customer table has 5 columns(Name,Family,CustZip,CustCity,CustAVGBal) I wrote the query like below is this correct? SELECT CustCity,LEFT(CustZip,5) AS NewCustZip,CustAVGBal FROM Customer WHERE CustCity = 'WA' THANKS!!

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  • android SQLite vs Flat Files

    - by mixm
    hi. im creating a game right now and im a bit stuck on how to implement storage of levels. i need to be able to download level files from the internet ota. im not so familiar with transferring files ota, but i have some experience with databases (mysql). what would be a better way of storing the game's level data?

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  • IF I have multiple candidate keys which one is a primary key and justify your choice ??

    - by zahrani
    Given R = { Account , Analyst , Assets, Broker, Client, Commission, Company, Dividend, Exchange, Investment, Office, Profile, Return, Risk_profile, Stock, Volume} and a set of functional dependencies F{fd1, fd2,fd3, fd4, fd5,fd6, fd7, fd8, fd9, fd10, fd11} where: fd1: Client - Office fd2: Stock - Exchange, Dividend fd3: Broker - Profile fd4: Company - Stock fd5: Client - Risk_profile, Analyst fd6: Analyst - Broker fd7: Stock, Broker - Invenstment, Volume fd8: Stock - Company fd9: Investment,Commission - Return fd10: Stock, Broker - Client fd11: Account - Assests these are candidate key(s) : (Account, Commission,Analyst ,Company) (Account, Commission,Analyst ,Stock) (Account ,Commission,Broker ,Company) (Account ,Commission,Broker ,Stock) (Account ,Commission,Client, Company) (Account ,Commission,Client ,Stock) (Q) Select a primary key and justify your choice ? I was select (Account ,Commission,Broker ,Stock) as a primary key ??? I chose that because it has the most direct dependencies compared to other ones. e.g. more attributes are functionally dependent on this primary key. please check if my answer is it true ? or Not I'm waiting your answer asap thank you

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  • Language/Framework support for Interacting With CouchDB

    - by Gordon
    I am interested in knowing if there are any server-side web application frameworks which integrate nicely with CouchDB? Does anyone have any experience in doing this? It seems like a dynamic language would be well-suited for playing with the JSON, but I am more interested in hearing about how it would fit in with the framework and the application's design.

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  • C# Find out what column caused the Sql Exception

    - by PaN1C_Showt1Me
    Hi. I'm getting an exception from SQL Data Reader (MS SQL as datastore) and I'd like to know which column name causes this Exception to be thrown. But I cannot find it in the InnerException.. nowhere. ((System.InvalidOperationException)ex.InnerException).StackTrace: System.Data.SqlClient.SqlDataReader.ReadColumnHeader(Int32 i) System.Data.SqlClient.SqlDataReader.IsDBNull(Int32 i) ... Where is it hidden please ?

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  • Why are there so many DB management Systems ?

    - by mr.bio
    Hi there , i always asked myself. Why are there so many DB management systems? I am not an DB expert and i never thought about using another DB than mysql. Programming languages offer different paradigms, so there it makes sense to choose a specific language for your purpose. What are factors to choose a specific DB management system ?

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  • Get current updated column name to use in a trigger

    - by Serge
    Is there a way to actually get the column name that was updated in order to use it in a trigger? Basically I'm trying to have an audit trail whenever a user inserts or updates a table (in this case it has to do with a Contact table) CREATE TRIGGER `after_update_contact` AFTER UPDATE ON `contact` FOR EACH ROW BEGIN INSERT INTO user_audit (id_user, even_date, table_name, record_id, field_name, old_value, new_value) VALUES (NEW.updatedby, NEW.lastUpdate, 'contact', NEW.id_contact, [...]) END How can I get the name of the column that's been updated and from that get the OLD and NEW values of that column. If multiple columns have been updated in a row or even multiple rows would it be possible to have an audit for each update?

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  • MSSQL: Primary Key Schema Largely Guid but Sometimes Integer Types...

    - by Code Sherpa
    OK, this may be a silly question but... I have inherited a project and am tasked with going over the primary key relationships. The project largely uses Guids. I say "largely" because there are examples where tables use integral types to reflect enumerations. For example, dbo.MessageFolder has MessageFolderId of type int to reflect public emum MessageFolderTypes { inbox = 1, sent = 2, trash = 3, etc... } This happens a lot. There are tables with primary keys of type int which is unavoidable because of their reliance on enumerations and tables with primary keys of type Guid which reflect the primary key choice on the part of the previous programmer. Should I care that the PK schema is spotty like this? It doesn't feel right but does it really matter? If this could create a problem, how do I get around it (I really can't move all PKs to type int without serious legwork and I have never heard of enumerations that have guid values)? Thanks.

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  • A B+tree simple implementation in C

    - by initpy
    Hi guys, I'm working on a fun project where I need a simple key/value store that uses B+Trees. I studied them some years ago, and to be honest, I don't want to reinvent the wheel, so I'm looking for a simple implementation in C of b+tree that I can just include in my project. I know of sqlite's, dbm's and tokyocabinet's ones but they're a little too "complicated" for my needs. Is there any (even pedagogical) work on this you can refer me to? Do you have some code to share? Thanks a lot!

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  • Oracle join query

    - by Jasim
    There are three tables in my db ITEM_MASTER, PRICE_MASTER, COMP_MASTER ITEM_MASTER STORE_CODE ITEM_CODE ITEM_DESC 011 914004 desccc PRICE_MASTER STORE_CODE ITEM_CODE COMP_CODE 011 914004 01 011 914004 02 011 914004 03 011 914004 04 COMP_MASTER COMP_CODE COMP_DESC STORE_CODE 01 comp1 011 02 comp2 011 03 comp3 011 04 comp4 011 I want to get all these for an ITEM_CODE in single query STORE_CODE ITEM_CODE ITEM_DESC COMP_DESC1 COMP_DESC2 COMP_DESC3 COMP_DESC4 011 914004 desccc comp1 comp2 comp3 comp4 How can i write a oracle SQL query for this??

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  • SQL - First row inserted every day for the past X days

    - by okie.floyd
    A tough SQL question (I'm using postgres by the way). I need the first row inserted every day for the past X days. one of my columns is a timestamp, which i hold the time inserted, and another column is the row id. If it's not possible to get the first row inserted every day, i at least need a unique one; a single row for every day for the past x days. Any suggestions? Thanks okie

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  • Setting 0/1-to-1 relationship in SQLAlchemy?

    - by Timmy
    is there a proper way of setting up a 0/1-to-1 relationship? i want to be able to check if the related item exists without creating it: if item.relationship is None: item.relationship = item2() but it creates the insert statements on the if statement

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  • When to use SQL Table Alias

    - by Rossini
    I curious to know how people are using table alias. The other developers where I work always use table alias, and always use the alias of a, b, c, ect. Here's an example SELECT a.TripNum, b.SegmentNum, b.StopNum, b.ArrivalTime FROM Trip a, Segment b WHERE a.TripNum = b.TripNum I disagree with them, and think table alias should be use more sparingly. I think it should be used when including the same table twice in a query, or when the table name is very long and using a shorter name in the query will make the query easier to read. I also think the alias should be a good name instead of a letter. In the above example if I felt I needed to use 1 letter table alias I would use t for the Trip table and s for the segment table.

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  • NHibernate, each property is filled with a different select statement

    - by Eitan
    I'm retrieving a list of nhibernate entites which have relationships to other tables/entities. I've noticed instead of NHibernate performing JOINS and populating the properties, it retrieves the entity and then calls a select for each property. For example if a user can have many roles and I retrieve a user from the DB, Nhibernate retrieves the user and then populates the roles with another select statement. The problem is that I want to retrieve oh let's say a list of products which have various many-to-many relationships and relationships to items which have their own relationships. In the end I'm left with over a thousand DB calls to retrieve a list of 30 products. Thanks. I've also set default lazy loading to false because whenever I save the list of entities to a session, I get an error when trying to retrieve it on another page: LazyInitializationException: could not initialize proxy If anybody could shed any light I would truly appreciate it. Thanks. Eitan

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  • How to make Django work with unsupported MySQL drivers such as gevent-mysql or Concurrence's MySQL d

    - by Continuation
    I'm interested in running Django on an async framework like Concurrence or gevent. Both frameworks come with its own async MySQL driver. Problem is Django only officially supports MySQLdb. What do I need to do to make Django work with the MySQL drivers that come with gevent or Concurrence? Is there a step-by-step guide somewhere that I can follow? Is this a major undertaking? Thanks.

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  • Django: How/Where to store a value for a session without unnecessary DB hits

    - by GerardJP
    Hi all, I have an extended userprofile with AUTH_PROFILE_MODULE (ref: http://tinyurl.com/yhracqq) I would like to set a user.is_guru() method similar to user.is_active(). This would results for al views (or rather templates) to e.g. disable/enable certain user messages, displaying of widgets, etc. The boolean is stored in the extended user profile model, but I want to avoid hitting the DB for every view. So the questions is .. Do I use a context_processor, a template tag, session_dict or what have you to, possible cached, store this info for the duration of the users visit. Note: I dont have performance issues, so it's definitely filed under premature optimization. I just want to avoid generating extra work in the future :). Any pointers are very welcome. Thanx and greetz! Gerard.

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