count and NULLs The Oracle SQL count function can be used to count either rows or fields in SQL queries. This article provides some examples on using the count function in both simple queries and in those that use aggregate functions and group a result set. Before going any further, you need to prepare your working environment. In particular, you...
Oracle
Using Non-Equi Joins
Using Non-Equi Joins Non-equi joins are those ones where the join condition uses an inequality comparison. This can be useful when defining self joins – ones defined on the same table. Suppose you have a table whose rows contain information about football teams. You need to make up a schedule for a series of games where each team is to...
Setting Up Oracle Database 12c on Oracle VM VirtualBox
Setting Up Oracle Database 12c on Oracle VM VirtualBox This article explains how to get started quickly with Oracle Database 12c installed in a virtual machine running on Oracle VM VirtualBox. In particular, you will look at how to install a VM, taking advantage of the pre-built Oracle Linux 6 Admin VM. Then, you’ll walk through the process of installing...
Exposing Oracle Database Data Via Oracle XML DB HTTP Server
Exposing Oracle Database Data Via Oracle XML DB HTTP Server By Yuli Vasiliev If you have ever used Oracle XQuery, you already know that this tool is really good when it comes to accessing external sources and bringing data extracted from them into your Oracle database. Sometimes, however, you may need to expose data stored in your Oracle database to...
Querying Relational Data With XQuery
Querying Relational Data With XQuery By Yuli Vasiliev This article illustrates how you might query relational data with Oracle XQuery. It also shows how you might join relational data with XML in a single SQL query, thus demonstrating the Oracle Database’s ability to work with and combine together different format data. In the following example, you query the DEPARTMENTS and...
Generating Relational Data From XML With XMLTable
Generating Relational Data From XML With XMLTable By Yuli Vasiliev Starting with 10g Release 2, Oracle Database offers a full-featured, native XQuery engine integrated with the database that can be used to accomplish various tasks involved in developing XML-enabled applications. With the help of Oracle XQuery you can construct XML data using SQL/XML functions XMLQuery and XMLTable, which provide a...
Transforming XML Data With XMLQuery in Oracle Database
Transforming XML Data With XMLQuery in Oracle Database By Yuli Vasiliev With a full-featured, native XQuery engine integrated with Oracle Database starting with 10g Release 2, you can accomplish various tasks involved in developing XML-enabled applications. With the help of Oracle XQuery you can construct XML data using SQL/XML functions such as XMLQuery and XMLTable, which provide a general interface...
Data, Information, and Business Intelligence
Data, Information, and Business Intelligence By Yuli Vasiliev In a BI system, information you need can be derived from different data sources, and by different means. Once it’s been derived, however, it doesn’t matter where it has come from, thus allowing consumers concentrate on the business aspects rather than on the specifics of the internal structure. It’s important to realize,...
Testing Oracle Database With Pre-built VM
Testing Oracle Database With Pre-built VM By Yuli Vasiliev You don’t have to prepare your system, download, and then install an Oracle database to be able to test it. You can significantly simplify the database installation process by using the pre-built Database App Development VM appliance running within Oracle VM VirtualBox. This appliance is available for download from the Pre-Built...
Database Tables Holding Data in Oracle XML DB Repository
Database Tables Holding Data in Oracle XML DB Repository By Yuli Vasiliev This article illustrates how you might query the XMLType tables that hold the data available via Oracle XML DB Repository. In particular, you’ll look at how you might optimize XQuery queries that use functions fn:doc and fn:collection to reference the repository data, accessing the underlying storage tables directly...