We human beings communicate with each other with the help of language. Similiarly, SQL stands for Structured Query Language is the language that a database understands, and we will communicate to the database using SQL. SQL is a 4TH generation database gateway language standardized by ANSI (American National Standards Institute) for managing data held in a RDBMS (Relational Database Management Systems).
The Data Definition Language (DDL) manages database table and index structure. The most basic commands of DDL are the CREATE, ALTER, RENAME, DROP and TRUNCATE statements.
The Data Manipulation Language (DML) manages data operation like INSERT, UPDATE, DELETE to database tables. The most basic commands of DML are the INSERT, UPDATE, DELETE and MERGE statements.
Structured Query Language (SQL) can be further subdivided in multiple parts based on its functionality. Data Query Language (DQL) mainly deals with SQL SELECT statement for retrieving data from a database.
SQL is a language for accessing and manipulating database standardized by ANSI. To be successful with database-centric applications (which includes most of the applications Data Warehousing domain), one must be strong enough in SQL. In this article, we will learn more about SQL by breaking the subject in the form of several question-answer sessions commonly asked in Interviews.
In this article we will generate complex XML tags/file directly from Database tables using simple SQL SELECT statement. Almost every database vendors provides support for XML read and write functionality. So let us exploit the available database xml functions. In this article we will demonstrate an use-case based on PostgreSQL database.
PostgreSQL is an advanced open source relational database management system. EDB develops and integrates performance, security, and manageability enhancements into PostgreSQL to support enterprise-class workloads for its database, EDB Postgres Advanced Server. EDB has also developed database compatibility for Oracle to facilitate the migration of workloads from Oracle to EDB Postgres and to support the operation of many Oracle workloads on EDB Postgres.
Remember Codd's Rule? Or Acid Property of database? May be you still hold these basic properties to your heart or may be you no longer remember them. Let's revisit these ideas once again..
Normalization is a method of organizing data in a database to reduce data redundancy and eliminate any undesirable anomalies such as Update and deletion anomaly. There could be various degree or form of normalization and in this article we will learn them step by step with easy examples.
NoSQL is not the name of any particular database instead it refers to a broad class of non-relational databases that differ from classical relational database management systems (RDBMS) in some significant aspects, most notably because they do not use SQL as their primary query language, instead providing access by means of Application Programming Interfaces (API).
Despite the high demand in recent years for massively distributed databases with high partition fault-tolerance, the CAP theorem stipulates that it is actually impossible for a distributed system to provide consistency, availability and partition fault-tolerance guarantees simultaneously; a distributed system can satisfy at most any two of these guarantees at the same time, but not all three. Let's understand this in detail.
When it comes to relational database systems, we already know what is meant by ACID property of database. But what is the BASE property of NoSQL database? Let's understand BASE in this article.
Here is an easy to understand primer on Oracle architecture. Read this first to give yourself a head-start before you read more advanced articles on Oracle Server Architecture.
The Oracle external tables feature allows us to access data in external sources as if it is a table in the database. This is a very convenient and fast method to retrieve data from flat files outside Oracle database.
Oracle Spool for SQLplus command line utility, can be used in conjunction with OS to export data from Oracle to flat file.
The Oracle supplied PL/SQL package UTL_FILE used to read and write operating system files that are located on the database server.
How to push data from Oracle Table to external files? Well, external tables in Oracle provides a way to move data in as well as out of the database with the help of SQL*Loader and Data Pump functionality.
Oracle Analytic Functions compute an aggregate value based on a group of rows. It opens up a whole new way of looking at the data. This article explains how we can unleash the full potential of this.
Too often we become impatient when Oracle Query executed by us does not seem to return any result. But Oracle (10g onwards) gives us an option to check how long a query will run, that is, to find out expected time of completion for a query.
Do you wonder how to get information on all the active query in the Oracle database? Do you want to know what query is executed by which user and how long is it running? Here is how to do it!
Confused about how to understand Oracle Query Execution Plan? This 10 minutes step by step primer is the first of a two part article that will teach you exactly the things you must know about Query Plan.
This is the second part of the article Understanding Oracle Query Plan. In this part we will deal with SQL Joins.
AUTOTRACE is a beautiful utility in Oracle that can help you gather vital performance statistics for a SQL Query. You need to understand and use it for SQL Query Tuning. Here is how!
This article tries to comprehensively list down many things one needs to know for Oracle Database Performance Tuning. The ultimate goal of this document is to provide a generic and comprehensive guideline to Tune Oracle Databases from both programmer and administrator's standpoint.
SAP HANA: High-Performance Analytic Appliance (HANA) is an In-Memory Database from SAP to store data and analyze large volumes of non aggregated transactional data in Real-time with unprecedented performance ideal for decision support & predictive analysis.