Oracle is a powerful client/server tool for database management. We explain what is the meaning and definition of oracle within computing, the tool and the aids it offers to the developer.
Oracle is basically a client/server tool for database management, it is a product sold worldwide, although the great power it has and its high price makes it only seen in very large and multinational companies, as a rule.
In the development of Web pages the same thing happens as it is a very expensive system is not as widespread as other databases, for example, Access, MySQL, SQL Server etc.
Oracle, as we mentioned before, is based on client/server technology, so in order to use it, first it would be necessary to install the server tool (Oracle8i) and then we could attack the database from other computers with development tools such as Oracle Designer and Oracle Developer, which are the programming tools on Oracle.
The ORACLE database manager, emerged in the late 70’s and early 80’s. George Koch and his team of technical storm troopers were the first to land on the Oracle field in 1982, during a database management system evaluation process for a major commercial application George was designing and building.
When completed, the evaluation was described in Computer World as the most severe DBMS study ever done. The study was so rigorous with the vendors whose products George had studied that his words were echoed in the press as far away as New Zealand and in publications far removed from the field as the Christian Sciencia Monitor.
Oracle, then known as Relational Software, had just over 25 employees at the time and only a few major customers. However, when the study was completed, Oracle was declared the winner. George claimed that Oracle’s DBMS was technically the best product on the market. These statements were made at a time when very few people knew the meaning of the term “Relational”, and those who knew it (or thought they knew it) did not have much favorable things to say about it.
The Oracle Corporation company was then working to perfect its young product, to understand the kinds of features and functionality that could make it useful and productive in the business world. The effort contributed to its refinement. Some of Oracle’s features, such as the SQL*FORMS outputs were the result of that effort.
Oracle is basically a client/server tool for database management. It is a product sold worldwide, although its great power and high price means that it is only seen in very large, multinational companies, as a rule. In the development of Web pages the same thing happens: as it is a very expensive system it is not as extended as other databases, for example, Access, MySQL, SQL Server, etc.
Let’s now focus on what exactly Oracle is and how programming on it works. Oracle as I mentioned before is based on client/server technology, well, for its use it would be necessary first to install the server tool (Oracle 8i) and then we could attack the database from other computers with development tools such as Oracle Designe and Oracle Developer, which are the basic tools for programming on Oracle.
To develop on Oracle we use PL/SQL a 5th generation language, quite powerful to treat and manage the database, also as a rule we use SQL when creating a form.
It is logically possible to attack the database through the SQL plus built into the Oracle program package to be able to perform queries, using the SQL language.
IN SHORT, WHAT IS ORACLE?
It is a relational database manager that makes use of the resources of the computer system in all hardware architectures, to guarantee its maximum use in information-laden environments.
It is the set of data that provides the capacity to store and to go to these in a recurrent way with a model defined as relational. It is also a suite of products that offers a great variety of tools.
It is the largest and most used Relational Database Management System (RDBMS) in the world. Oracle Corporation offers this RDBMS as a product incorporated to the production line. It also includes four generations of application development, reporting tools and utilities.
Oracle runs on personal computers (PCs), microcomputers, mainframes, and computers with massive parallel processing. It supports about 17 languages, runs automatically on more than 80 different hardware and software architectures without having to change a single line of code. This is because more than 80% of Oracle’s internal code is the same as that established on all operating system platforms.
PHYSICAL AND LOGICAL STRUCTURE
Physical structures such as operating system files are stored on tangible devices such as magnetic tapes, disks and others. Each file has a corresponding space in the operating system. Oracle requires several files for its operation, which make up its physical structure.
The logical structure corresponds to a space per unit, but its limitations are independent of the physical space locations.
USE OF MEMORY
The use of memory in the Oracle RDBMS has the following purpose:
- To store the program codes to start running.
- To store the necessary data during the execution of a program.
- To store information about how the transfer between processes and peripherals is.
PROGRAMS AND FILES THAT MAKE UP ORACLE
An Oracle RDBMS is composed of three main parts, which are:
- The Oracle Kernel
- The instances of the Database System.
- The Files related to the Database System.
THE ORACLE KERNEL
The Kernel is the heart of the Oracle RDBMS, which handles the following tasks:
- Manage the storage and definition of data.
- Provide and limit data access and user concurrency.
- Enable data backup and recovery.
- Interpreting SQL and PL/SQL.
- Just as the Kernel is an operating system, the Oracle Kernel is loaded into memory at the beginning of operations and is used by each existing database in the equipment.
The EMP (Global Area Programme)
It is also called Global Process Area, and it consists of data and process control information, ensuring the correct use of these. The PGA contains information about the connections and processes that are carried out in Oracle, its size is variable in length, but it is not dynamic. The PGA is activated when a user connects.
The SGA (System Global Area)
It can be called the Shared Global Area. It could be defined as a series of resident memory buffers, through which all transactions and data storage flow. The WMS is located in memory when an instance is started and disappears when it is downloaded. Its size cannot be changed, but it can be seen with the command “SHOW SGA” in the SQL*DBA. Its length is defined by the parameters of the INIT.ORA startup file.
It is composed of:
- Dictionary Cache
- The Redo Log Buffers
- The Database Buffers
It is a set of tables that are used to provide information associated with the database, where the user names, privileges, objects, retentions and spaces that make up an Oracle RDBMS are defined.
REDO LOG BUFFERS:
It is a space reserved in memory that contains the changes made to the data blocks, allowing the reconstruction of the database in case of an accident.
It is a space reserved in memory for the normal operations of the database, which depends on the size specified in the initialization file (INIT.ORA).
DIFFERENT ORACLE TOOLS
SQLForms: is the Oracle tool that allows, in a simple and efficient way, to design screens for the entry, modification, deletion and querying of records. Once the form has been defined, the user can work with it without the need to generate codes, since Oracle has a set of procedures and functions associated with the function keys, such as the [F7] key, which is used to start a query.
The fundamental tool of SQL is the SELECT statement, which allows selecting records from the database tables, returning those that meet the established conditions and being able to present the result in the desired order.
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SQL (Structured Query Language)
The FROM command identifies the list of tables to query. If any of the tables to be queried are not owned by the user, the name of the owner must be specified before the name of the table in the form owner_name.table_name.
The WHERE command decides the records to be selected according to the established conditions, limiting the number of records shown.
The ORDER BY command indicates the order in which the query result appears.
Friends, we will leave this article for today, don’t miss part 2 where we will talk about query patterns in Oracle, data grouping, subqueries, indexes, structures, programs and files that understand it and much more. A big hug !