CS-GY 6083: Principles of Database Systems
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main
  • Introduction
  • DBMS Basics
    • Introduction to DBMS
    • Why use a DBMS instead of a File System?
    • Levels of Abstraction
    • Instances and Schemas
  • Data Models
    • Introduction to Data Models
    • Database Languages
    • Database Design
  • DBMS Internals
    • Introduction to DBMS Internals
    • Storage Manager
    • Query Processor
    • Transaction Management
    • Database Users
    • Database Architecture
  • DBMS History
  • Some Popular Database Systems
  • OLTP, OLAP, and Data Mining
  • Databases vs. Information Retrieval
  • The Entity-Relationship Model - Details
    • Introduction
    • Cardinality Constraints
    • ER Diagram Components
    • ER Diagram to Relational Schema
    • Design Issues
  • The Relational Model - Details
    • Relations
    • Keys
    • Relational Query Languages
      • Relational Algebra
      • Relational Calculus
      • Relative Expressive Power
    • Relational Operators
  • SQL
    • Introduction to SQL
    • Domain Types in SQL
    • DDL Commands
      • Creating a Table
      • Alter and Drop
    • DML Commands
      • Basic Query Structure
      • Select
      • From
      • Where
      • Joins
      • Rename
      • String Operations
      • Ordering
      • Set Operations
      • Group By and Having
      • Nested Subqueries
      • Test for Empty Relations
      • Test for Duplicate Tuples
      • Derived Relations
      • With
      • Database Modification
    • Intermediate SQL
      • Joins Revisited
      • Views
      • Transactions
      • Integrity Constraints
      • More SQL Data Types and Schemas
        • Other Features
      • Authorization
    • Advanced SQL
      • Accessing SQL From a Programming Language
        • ODBC and JDBC
        • Embedded SQL
        • PHP
        • Some Security Issues
      • Accessing Metadata
      • Text Operations
        • Like
        • Contains
      • Cursors
      • Functions and Procedures
        • Procedural Constructs
        • External Language Routines
      • Triggers
      • Ranking
      • Windowing
      • OLAP
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  • Data Manipulation Language (DML)
  • Data Definition Language (DDL)

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  1. Data Models

Database Languages

Broadly speaking, there are two categories of database languages:

  • Data Manipulation Language (DML)

  • Data Definition Language (DDL)

Data Manipulation Language (DML)

  • It is also known as query language

  • It is used to access and manipulate the data stored in a database

  • It has two sub-categories: procedural (the user specifies what data is required and how to compute the data) and declarative/non-procedural (the user specifies what data is required without specifying how to compute the data)

  • SQL (Structured Query Language) is the most widely used query language and is non-procedural

  • Some common DML commands include SELECT, INSERT, UPDATE, DELETE

Data Definition Language (DDL)

  • It is used to define the database schema, the storage structure, integrity constraints and the authorizations on the database content and operations

  • The DDL compiler generates a set of tables stored in a data dictionary

  • The data dictionary contains metadata including the database schema, the storage structure (specified using data storage and definition language), integrity constraints (such as domain constraints, referential integrity, assertions etc) and authorization information

  • Some common DDL commands include CREATE, ALTER, DROP

SQL is, therefore, both a DML and a DDL.

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Last updated 4 years ago

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