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DATABASE MANAGEMENT SYSTEM,DATA DEFINITION LANGUAGE
- 1. PRESENTED BY Ms. CHANDRAKUMARI SUBBA
- 2. What are Data& Databases? Data: It refers to any piece of information. Example: numbers, words, images, sounds, or any other information that a computer can store and process. Database: A database is a structured collection of data that is organized in a way to facilitates efficient storage, retrieval, and manipulation of information.
- 3. DATABASE MANAGEMENT SYSTEM(DBMS) A Database Management System (DBMS) is a software system that enables users to define, maintain, and manipulate databases. It provides an interface between the database and the users or applications, allowing them to access and manage data efficiently. The popular DBMS are MySQL, Microsoft Access, Oracle, Microsoft SQL Server.
- 4. The primary functionsof a DBMS: 1. Data Definition: Defining the database structure, including specifying data types, relationships between data elements, and constraints. 2. Data Manipulation: Inserting, updating, deleting, and retrieving data from the database using queries and commands. 3. Data Security: Enforcing access control to ensure that only authorized users can access and modify the data. 4. Data Integrity: Maintaining the accuracy, consistency, and reliability of the data through validation rules and constraints. 5. Concurrency Control: Managing simultaneous access to the database by multiple users or applications to prevent conflicts and ensure data consistency. 6. Backup and Recovery: Providing mechanisms for backing up data and recovering it in case of system failures or data corruption.
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- 6. A primary keyis a unique value that identifies a row in a table, whereas a foreign key identifies a column or set of columns in one (referencing) table that refers to a column or set of column in another (referenced) table. A table can have only one Primary Key but a table can have multiple foreign keys.
- 7. In adatabase you can define the structure of the data and manipulate the data using some commands. There are two types of languages for the task. These are: i. Data Definition Language (DDL) ii. Data Manipulation Language (DML) DDL Commands in SQL are: Create, Alter, Drop. DML Commands in SQL are: Select, Update, Delete, Insert.
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