I'm pretty new to databases, so forgive me if this is a silly question. In modern databases, if I use an index to access a row, I believe this will be O(1) complexity. But if I do a query to select another column, will it be O(1) or O(n)? Does the database have to iterate through all the rows, or does it build a sorted list for each col...
I am starting to learn ASP.NET MVC. I have deployed the "stock" ASP.NET MVC Sample Application (i.e. the simple user account system) to have a live version to test against when I start to play. Note that I'm using: - ASP.NET MVC 1.0 release. - WebFusion Host. I think the issue is to do with accessing the database. I deployed usin...
I have a class of data with a very large number of binary properties--151 (!) to be exact--and I am concerned with how to model this data structurally. Despite the internal efficiencies of storing bit-fields as bytes, my programming spidey senses are tingling at creating a table with 151 bit-fields (in addition to other properties). The...
Cannot get my head around the SQL that will return the number of times a user has accessed a particular service. Think it might require a nested count and select, but cannot get my head around it. The data looks like this: UserID Service --------------- 1 Map1 1 Map2 1 Map1 2 Map1 2 Map2 3 Map4 3 ...
How can I access a MS Access database from a remote server, which is on Windows platform, using Cocoa and objective-C on Mac OS X? The server is located in remote location and it can only be accessed over internet. How can I make connection with server over internet? what all procedures to be used for making such applications? If I need...
we are planning to implement sql server 2005 cluster in next few months. i wanted to know what steps / precautions need to be taken as a database developer when trying to achieve this? do we need to change any ado.net code (in front end) / stored procs etc etc? are there any best practices to be followed? reason i am asking this questio...
Hi all.. I have a question. I am having problems updating data in an SQL database with Windows Forms (Visual Studio project). Here is what I do: I get user information in text boxes. I edit some of them. I do 1 back n get to this form again. The info is updated. When I quit and login again, it shows me the old data! It seems as ...
We have to automate database updation couple of times a month. My current use case is as follows. Currently we manually diff the input data with the previous month's input. If it is XML we use MS xmldiff. If it is Pdf , it is fully done through manual verificaton :-( . Once the changes are found, we update the database through a fo...
Hi group: My requirements are: Relatively small database: 25-30 tables with 4-5k rows in each. 4-5 users with their own copies of local database on their laptops. Sync when needed or at the end of the day. Free solution, as am making this setup for a NFP ogranization. I have been researching various options in last few days. At last I ...
I have an Event table that specifies a date range with start_date and end_date fields. I have another date range, specified in code, that defines the current week as 'week_start' and 'week_end'. I'd like to query all Events for the week. The cases seem to be: Event begins and ends within the week Event begins before the week, but en...
Let's say I have a booking database consisting of users: user_id fname lname and their tickets ticket_id user_id flight_no and associated flights flight_no airline departure_time arrival_time What would I need to change to move this Google AppEngine? I understand AppEngine doesn't allow joins. Does that mean my table should be...
Hello all, I am having a difficult time deciding how to handle a business requirement in my database schema. I have a lot of tables in the database, but there are only three I need to deal with for this problem: Courses, PersonnelCourses, and Personnel. Courses is a list of Courses Personel is a list of Personnel PersonnelCourses is...
I'm designing a very simple (in terms of functionality) but difficult (in terms of scalability) system where users can message each other. Think of it as a very simple chatting service. A user can insert a message through a php page. The message is short and has a recipient name. On another php page, the user can view all the messages ...
I can never decide if it's better to format data before inserting it into the DB, or when pulling it out. I'm not talking about data sanitization; we all know to protect against SQL injection. I'm talking about if the user gives you a URL, and it doesn't have http:// in front of it, should you add that before inserting it into the DB or...
Hi, I'm looking for a way to script postgreSQL schema changes in an idempotent manner. In MSSQL I could do something like this: if(not exists(select * from information_schema.columns where table_name = 'x' and column_name = 'y')) begin alter table x add y int end go PostgreSQL doesn't seem to allow ad-hoc pl/pgsql in the same wa...
I'm creating an Access DB for use in an C# application at school. I've not had much experience working with DB's so if this sounds stupid just ignore it. I want the user to be able to select all the classes that a certain student has had in our IT department. We have about 30 in all and the maximum that a person can take in 4 years of hi...
I was wondering if anyone has a suggestion for what kind of storage engine to use. The programs needs to perform a lot of writes to database but very few reads. [edit] No foreign keys necessary. The data is simple, but it needs to preform the writes very fast. ...
I am developing an attendance management program, used to maintain the absence record of a student. Users of this software will need to enter various dates, updated once in a month: for instance, a list of dates on which a student was absent for that particular month would be entered, and my program must then store them into a database w...
With things like SO, Digg, Reddit, etc... Should one keep track of downvotes in the database independent of upvotes? Or should they simply have a "votes" field that is decremented/incremented based off what the user does with no persisting of that? How should votes be handled? ...
I have a table with a unique key (date + userid) in my webapp database. When i try to insert record with existing date and userid, i'm getting error "dupicate key in table". I turn on database debug in application config, because i need use mysql error number and message. And now i need processing this error. I can use hard coded constan...