Structured Query a Language (SQL)

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SQL stands for Structured Query Language. It is a special query language used to access and manipulate data in relational database management systems like MySQL, Oracle, and SQL Server. SQL allows you

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1. Numeric Types: INT (integers), FLOAT (decimal numbers) 2. String Types: CHAR(n) (fixed length), VARCHAR(n) (variable length) 3. Date and Time Types: DATE (YYYY-MM-DD format) Example: CHAR(10) reser

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Constraints are restrictions on data values that attributes can have to ensure data correctness. Five common constraints: 1. NOT NULL - prevents empty values 2. UNIQUE - ensures all values are distinc

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CREATE DATABASE databasename; USE databasename; Example: CREATE DATABASE StudentAttendance; USE StudentAttendance; Note: Database names are case-sensitive in Linux but not in Windows.

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CREATE TABLE tablename( attribute1 datatype constraint, attribute2 datatype constraint, ... PRIMARY KEY (attribute_name) ); Example: CREATE TABLE STUDENT( RollNumber INT, SName VARCHAR(20

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ALTER TABLE table_name ADD FOREIGN KEY(attribute_name) REFERENCES referenced_table_name(attribute_name); Example: ALTER TABLE STUDENT ADD FOREIGN KEY(GUID) REFERENCES GUARDIAN(GUID); Important: Refe

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All attributes: INSERT INTO tablename VALUES(value1, value2, ...); Specific attributes: INSERT INTO tablename(column1, column2) VALUES(value1, value2); Example: INSERT INTO STUDENT VALUES(1, 'Atharv

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SELECT attribute1, attribute2, ... FROM table_name WHERE condition; - SELECT: Specifies which columns to retrieve - FROM: Specifies the table name (mandatory) - WHERE: Filters rows based on condition