database

How to get ERD diagram for an existing Database?

i have a DB in PostgreSQl i want to get its erd how can i do so thanx in advance ...

how to access path of database or file of different app in android

Is it possible to get path of database file in android at path : "/data/system/accounts.db" in my app i want to use this database, but not getting its path. if i do hardcoding and remove the file i'm able to do it. But i want to access it as database so that i can drop the table. Any help would be appreciable. code i tried: priva...

why wordpress using two column to store post date

I see wordpress database on wp_posts table, there are 2 columns to store post date, post_date and post_date_gmt post_date_gmt store the post date in GMT time. And post_date store post date in user time who create the post. Am I right? Is there any benefit to store both version of post date on database? Is it faster to store both versi...

How do I Handle Database changes and port my data?

Example, for web applications using Turbogears and SQLAlchemy. Every time I update my data model, I need to delete my database and recreate it. Is there an easy way to update the production database? Do I have to write a custom script that transfers all the production data into a new database model? Or is there an easier way to upgra...

Is there a performance decrease if there are too many columns in a table?

Is there some performance loss if one of tables in my database has huge amount of columns? Let's say I have a table with 30 columns. Should I consider splitting the table into few smaller ones or is it ok? What is a recommended maximum amount of columns per database table? Thank you. ...

Store and retrieve friends contact list using mysql

Hi I want to create a database that can store the friends contact list as like social networking what is the best way to design the database structure and easy to retrieve the contacts of friends using mysql. i need solution for this, HELP ME regards ~Deepu~ ...

Ruby on Rails database.yml information

I'm a designer and brand new to programming. I have just opened my localhost and can see "Welcome aboard". It has 3 steps to complete - all of which simple to most, are complexing to me. config/database.yml ok it wants to know my username and password. Where do I get these and where do I post them to to get them to work? I opened my d...

[Drupal] Manipulating database data from front-end

Let's say a content-type user has a CCK field called friends. From the back-end (as admin) you can easily multiselect the friends of that user. But how can i change the value of this field by a button 'Add as friend' on the detailpage of this user on the front-end. Summary: How can i manipulate node data from the front of the webpage?...

MySQL - Show All Permutations?

Table1: Id MyFK f_name l_name =========================== 1 100 John Doe 2 100 Little Timmy Table2: Id MyFK item price =========================== 1 100 Car 200 2 100 Bike 100 In MySQL, how do I produce a table like this: Id MyFK f_name l_name item price ================...

Good Pivot Table / Data Table algorithm in Java

I have a database to access via JDBC which returns around 200k of records I have to consolidate data table style for further processing. I could if that leads to good performance send a few SELECT (Count(...) ...) statements upfront. What is a good algorithm in Java to compute such a pivot table? ...

Android SimpleCursorAdapter and Database Update

Hi All, I just started with Android development and love it so far. To get some experience, I am writing a little todo application. In my database I have a state for a todo item, represented as int. I use a checkbox in a list view to represent this state. To bind the data to the view, I use a subclass of SimpleCursorAdapter. I add an on...

Databases allow bad foreign keys from Rails Fixtures

Hi, I am using Rails Fixtures to load some test data to my database and accidentally I introduced a foreign key out of range. To my surprise, the database accepted it despite having referential integrity constraints (that work). I tried with PostgreSQL and with MySQL InnoDB and both allowed. Example: Having in the database "Flavour...

Assigning a user to multiple projects in my PHP application, best approach?

I am currently building a web application for my work and you can add tasks, projects and clients. The dilemma I've encountered is that a client can be assigned to multiple projects at once. The application is being built upon the latest version of Codeigniter 2.0 (if that helps). I am usually pretty good at working out problems like th...

MySQL's ibdata file is getting big and the size doesn't reflect how much data I have.

The size of MySQL ibdata is 4GB, but I don't think the data I have should take that much disk space. I am using MySQL InnoDB storage engine. Am I doing something wrong with configuration? How do I reclaim the disk space because deleting rows didn't help at all? Thanks ...

ASP - Microsoft Access Providers - userID unique after deleting user or reuse?

Hello, I'm building a website in ASP (C#). I'm using the Microsoft Access Membership Provider. I was wondering if the userID will stay unique after removing the user or if it will be used again when creating a new user. Hope somebody knows the answer. Greet, Jesper ...

database,sql server, sql which key?

I have 1 table with 6 columns lets call them A B C D E F They can be null or a value but that once have a value entered in any row of any column it must be null or unique and validated by the database what key or constraint could I use to achive this? ok real life scenario-- I have a product this is carrots the carrot can have upto 6...

SQLITE + CHROME/SAFARI: "not authorized" ERROR

I am trying to do a bulk transaction using SQLITE on CHROME (and SAFARI). I'm doing this with javascript so this is what I have: ============================================================= query = "BEGIN TRANSACTION; " query += "INSERT INTO schools (name) VALUES('School 1');" query += "COMMIT TRANSACTION;" db.executeSql(query); ...

What should I choose: MongoDB/Cassandra/Redis/CouchDB?

Hi, We're developing a really big project and I was wondering if anyone can give me some advice about what DB backend should we pick. Our system is compound by 1100 electronic devices that send a signal to a central server and then the server stores the signal info (the signal is about 35 bytes long). How ever these devices will be se...

Rails record versioning solution

I'm looking for a solution to version database changes in rails. Looking for something very basic. I mean like a wiki or SO edit versioning. ...

CodeIgniter, active records, JOIN help?

I am trying to figure out why my JOIN is not working on a database query, I have two tables with a user_ID column, but when I return this it returns everything, not just the selected ones per user. What am I messing up any thoughts? Thank you! function user_apps() { $this->db->select('*'); $this->db->from('apps'); $this->db...