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Unit 2: Introduction to SQL and its Characteristics

Lesson 13 of 28 in the free Database Management Systems notes on Siksha Sarovar, written by Rohit Jangra.

13.1 Overview of SQL

SQL (Structured Query Language) is the standard language used to communicate with Relational Database Management Systems (RDBMS). It was originally developed by IBM in the 1970s (originally called SEQUEL) and has since become the universal standard for data management.

13.2 Characteristics of SQL

CharacteristicDescription
Non-ProceduralSQL tells the database what to do, not how to do it. The DBMS handles the optimization and execution.
English-like SyntaxUses common keywords like SELECT, INSERT, UPDATE, and DELETE, making it readable.
Universal StandardSupported by almost all RDBMS (MySQL, Oracle, SQL Server, PostgreSQL).
Set-OrientedSQL operates on sets of rows at a time rather than individual records.
DynamicData structure can be modified while the system is running.

13.3 Advantages of SQL

  1. High Speed: SQL queries can retrieve large amounts of data very quickly.
  2. No Coding Required: Complex data retrieval doesn't require thousands of lines of code; simple queries suffice.
  3. Portability: SQL code used in one RDBMS can often be moved to another with minimal changes.
  4. Interactive Language: It can be used both for writing complex scripts and for ad-hoc interactive queries.
  5. Multiple Data Views: Different users can see different perspectives of the same data structure.

13.4 History and Standards

  • SQL-86: The first official standard.
  • SQL-92 (SQL2): A major revision that added many features.
  • SQL:1999 (SQL3): Added Object-Oriented features and triggers.
  • Modern SQL: Continues to evolve with support for XML, JSON, and Big Data features.