Database 2

Types of Databases #

1. File System: A data management method that precedes databases, where files are named, and their logical locations for storage or retrieval are defined and managed.

ISAM #

A system where data content is stored in the primary storage, and data indexes, along with the data's recorded location, are stored in the index section.

VSAM #

A file management system used in large operating systems.

2. Hierarchical Database (HDBMS)

   • A database that manages data by hierarchically structuring it in parent-child dependent relationships.
   • It offers fast data access, but due to its dependent structure, it's not easy to flexibly adapt to changing data structures.

3. Network Database Management System (NDBMS)

   • A data model that logically represents data structures in a network-like form.
   • It is more flexible than tree structures or hierarchical databases, but it has the disadvantage of complex design.
   • Products include IDS, TOTAL, and IDMS.

4. Relational Database Management System (RDBMS)

   • The most common database management system.
   • It organizes correlations by representing parts of data-storing tables in parent-child relationships with other tables.
   • It offers good flexibility for changing business requirements and data structures, making maintenance easy.

5. NoSQL (Not Only SQL)

   • It uses a less restrictive consistency model than traditional relational databases and is used for big data and commercial real-time web applications.

Characteristics of Database Management Systems (DBMS) #

• Data Integrity: The property of not allowing inappropriate data to be entered, preventing different data from being stored for the same content.
• Data Consistency: The property that stored data must remain constant and unchanged even after insertion, deletion, update, or creation.
• Data Recoverability: The property that data must be restored to a specific state in the event of a failure.
• Data Security: The property that data must be protected from illegal exposure, alteration, or loss.
• Data Efficiency: The property that response time, storage space utilization, etc., must be optimized to satisfy the requirements of users, software, and systems.

Database Management System Classification #

1. Classification by System Characteristics

• Relational Databases

  Oracle, MySQL, MS SQL Server, PostgreSQL, DB2, Maria DB

• Document Store DBMS

  MongoDB, Amazon DynamoDB, Couchbase, MS Azure Cosmos DB

• Graph DBMS

  Neo4j, MS Azure Cosmos DB, Orient DB, Arango DB

• Key-Value DBMS

  Redis, Amazon DynamoDB, Memcached

2. Classification by Commercialization and Open Source

• Commercial DBMS: Software created for commercial purposes or for sale.
• Open Source Based DBMS: Software made public and usable without restrictions.

Database Management #

Database Operations #

• CRUD refers to the basic data processing functions of a database: Create, Read, Update, and Delete.

1. Data Insertion
   • To insert data into a table, use the Insert command.

INSERT INTO table_name
VALUES(value1 , value2, value3, ...);

2. Data Reading
   • To read data from a table, use the Select command.
   • Using * after Select reads all data, while specifying column names reads only specific columns.

SELECT column1 , column2, ...
FROM table_name;

3. Data Update
   • To update data in a table, use the Update command.
   • You must specify the data to be updated using the WHERE clause.

UPDATE table_name
SET column1 = value1, column2 = value2, ...
WHERE condition;

4. Data Deletion

   • To delete data from a table, use the Delete command.
   • You must specify the data to be deleted using the WHERE clause.

5. Other SQL Commands

   • Modify a database using the ALTER DATABASE command.
   • Modify table structure using the ALTER TABLE command.
   • Delete an entire table using the DROP TABLE command.
   • Create an index to improve data search speed within a table using the CREATE INDEX command.
   • Additionally, various commands such as UNION and GROUP BY are used.