I am studying relational algebra these days and I was wondering... Don't you thing it would be better if a compiler was existed which could compile relational algebra than compiling SQL? In which case a database programmer would be more productive? Is there any research on relational algebra compilers? Thanks in advance ...
I'm building a small application and setting up foreign key relationships between tables. However I'm confused as to WHY I really need this? What is the advantage - does it assist me when writing my queries that I don't have to perform any joins? Here's an example snippet of my database: +-------------------+ | USERS | +----...
I would like to know if its possible? Step1: call one web service A which retrieves data from the database and stores in a result set (dynamically) Step2: web service A calls web service B to process the data stored in the result set. Is it possible to share result sets which could be of large or small size between web services. If it...
I am trying to secure online transaction between application server and database. One-way is SSL, but is there any other way of securing transaction between them. I am trying to reduce the overhead in securing the line. Are there any tool or api's which I can integrate with the application server or deploy on it. /SR ...
I have a system comprising 5 applications. Each app accesses a database via a DAL library. In the DAL i have an app.config with the following entry: <connectionStrings> <add name="DataAccessLayer.Properties.Settings.ConnectionString" connectionString="Data Source=.\SQLEXPRESS;AttachDbFilename=c:\users\something\something\MyDB.mdf;Inte...
I have an HTML/XML table generated by AJAX that displays limited columns of a database table. I would like to filter rows of the HTML/XML table using columns from the database that aren't part of the HTML table. Example: MySQL tables (ignore bad syntax): TABLE technicians (id, name, email, ...
I am currently working on a project which has Employee, Manager entities. At the very beginning, I took for granted that a manager must be an employee in the company, so they are the same person who have the same EmployeeID in payroll system. Based on this assumption, I let the Manager class extends Employee class. Later, my client tol...
I have a data structure that looks like this: Model Place primary key "id" foreign key "parent" -> Place foreign key "neighbor" -> Place (symmetryc) foreign key "belongtos" -> Place (asymmetric) a bunch of scalar fields ... I have over 5 million rows in the model table, and I need to insert ~50 million rows into ...
Sometime ago, when I installed Oracle on Ubuntu, there was a sample database. Database contained Employees, Departments, ... Now I wonder is there something similar for MySQL? ...
Is it possible to connect database with javascript. ...
I am creating sql queries and I have read in one book that when using NOT operator or LIKE operators Indexes do not work. How much true this statement is. How can we avoid this if the statement is true. How a query should be made to do the same work avoiding these operators. What all other areas are there in sql server where Indexes are...
Hi, I have a problem with my code. As you can see i Try to have a sort of CHECK constraint using two columns in the same table but seems does not work. My need is to accept value in EffectiveEndDate only if they are > that EffectiveStartDate. Any idea how to solve it? thanks for your support! :-) CREATE TABLE dbo.Test ( EffectiveSt...
Friends, I am inserting the xml parsed data into database table,i have the following fields, name,price,image, Static insert of name addevent("name",price,image); it's getting inserted well,where i given name field has static. 2.Dynamic insert of names. But when insert the field data from xml parsed value (name) - String , it's be...
CREATE PROCEDURE A(tab IN <table - what should I write here?>) AS BEGIN INSERT INTO tab VALUES(123); END A; How can I specify that the parameter tab is a table name? ...
Hi All, I am looking for some refrerence which can help me in finding out the ddl differences in muliple databases (Oracle, DB2, Syabase,MSSql,My Sql, Firebird, PostgreSql,Ingres,HSQL, H2 Database, Derby). What all constraints are supported by each database Whether table/column comments are supported or not Auto increment of column is...
Hi, Ruby on Rails ORM(object relational mapping) has a thing call polymorphic associations that allow a foreign key to be used to reference 2 or more other tables. This is achieved by creating an additional column called "type" that specifies the table with which the foreign key is associated with. Does this implementation have a name f...
Hi, I am building a website with individual user customization in mind. So for instance, client #1 may say i want this feature to be designed for my account and then user #2 may say i want this added to my account. I was thinking of implementing a php if code where upon authentication those features will be loaded each time they login...
Hi all. I am trying to work with dates in an sqlite database. I am storing my dates as timestamps, but when I use strftime() to format them to human readable dates I am getting back unxpected results. Condider the following, I select the current timestamp: SELECT strftime("%s","now"); 1281353727 Then I try to format a date using th...
From this article about index organized tables, Note that rebuilding a secondary index on an index-organized table involves reading the base table, unlike rebuilding an index on an ordinary table. Why does rebuilding of an index on an ordinary table not require reading the base table? ...
For example, if I do SELECT ROWID, name from emp where age > 30; As ROWID does not take any storage space, is it calculated every time a query like this runs? From here, Each table in an Oracle database internally has a pseudocolumn named ROWID. This pseudocolumn is not evident when listing the structure of a table by ...