Database Constraint Conditions Default Value Constraint CREATE TABLE user_data(user_id INT, username VARCHAR(32) DEFAULT 'john'); Zero Fill Constraint CREATE TABLE sample_table(id INT ZEROFILL); Unsigned Constraint CREATE TABLE numeric_data(value_id INT UNSIGNED); Not Null Constraint CREATE TABLE em...
Databases function as structured repositories for persistent data management. Unlike transient memory variables or isolated local files, database systems enable concurrent access, network sharing, and robust integrity controls. Systems are broadly categorized into relational and non-relational archi...
The NOT NULL constraint acts as a rule enforcing that a specific column cannot store undefined or missing values. This restriction is fundamental for maintaining data integrity, ensuring that every record in the database contains essential information for designated fields.Applying this constraint d...
SQL (Structured Query Language) manages data in relational database management systems (RDBMS). It supports inserting, querying, updating, deleting data, creating and modifying schemas, and controlling access. A relational DBMS stores data in tables composed of rows and columns. Each table represent...
Database Fundamentals Why Learn Databases? Previously, to store data permanently, we used I/O streams to write data to local files. However, tasks like changing a specific user's age in a text file were cumbersome, requiring reading lines, creating objects, modifying them, and writing back. Database...
Understanding Relational Databases with MySQL A relational database organizes data into structured tables composed of rows and columns. MySQL is a widely used open-source relational database management system (RDBMS) that implements this model. Core Concepts Database: A container holding related tab...
PyMySQL is a library for connecting to MySQL servers from Python 3.x, replacing MySQLdb used in Python 2. Install it using pip: pip install pymysql Core Methods in PyMySQL pymysql.connect() parameters: host (str): MySQL server address port (int): MySQL server port user (str): database usernmae passw...
Core Concepts of Structured Query Language Structured Query Language (SQL) serves as the universal interface for interacting with relational databases. Its capabilities extend beyond simple queries to encompass schema definition, data manipulation, security enforcement, and integrity control. This m...
Sample Tables Table X CREATE TABLE X ( user_id INT, username VARCHAR(20), profile VARCHAR(20) ); INSERT INTO X VALUES(1, 'Alice', 'Dev'); INSERT INTO X VALUES(2, 'Bob', 'QA'); Table Y CREATE TABLE Y ( user_id INT, username VARCHAR(20), score INT ); INSERT INTO Y VALUES(1, 'Alice', 85); INSERT INTO Y...
Problem Statement When performing time-based data analysis, there's often a need to align timestamps to predefineed interval boundaries. For instance, given a timestamp like 2024-03-26 14:25:59, you might want to group it into 30-minute buckets, resulting in 2024-03-26 14:00:00. This operation is co...