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.