Last Updated on June 20, 2024 by GeeksGod
Course : SQL complete Bootcamp From Basics to Advanced,Sql interview
Why SQL
Store large number of records
Share huge data set among many people
Add and edit data easily
Quick and easy to find information
RDBMS TERMINOLOGY
Column as Attribute
Row as Entity Instance
Table as Entity
AlternateKey as UniqueKey
RELATIONSHIPS Cardinality
90% of the tables in database will be linked with another tables.
10%of the tables will be independent.
There are three types of relationships between tables
one to one
one to many
many to many
Tables can have a single / multiple relationships or may not have relationships.
Structured data – 2 dimensional data Rows,Columns
PrimaryKey in one table will be given as ForiegnKey in another table to build relationship.
DATA MODELING
RDBMS
PrimaryKey & ForiegnKey with relationship between them.
1 to 1 – any PrimaryKey can become ForiegnKey
1 to many employees in a department
PK of parent table will be FK in child table
Department table Deptid(PK),DeptName,
Employees Table Empid,EmpName,DeptId(FK)
many to many(students and teachers,patients & doctors,Hospital & Doctors)(TeacherId,TeacherName)(StudentId,StudentName,TeacherId)
New table will be created and extra column will be added(Bridge Table)
Patient Table(PatientNo(PK),PatientName,Adress),
Doctors Table(DoctorNo(PK),Name,Qualification,Salary, DateOfJoining, DateOfResigning)
Patient Doctor Table()
SDLC-Software Development Life Cycle
Requirement
Analysis & Design
Development
Testing
Release
Domain expert(SRS documentation)
Architect
SQL developers
Testers
Deployers(TL/Manager)
ERD(Entity Relationship Diagram)
Peter Chan-Used to design Database
Referential Integrity
SQL server performs existence check when we create relationship.
SELF REFERENTIAL TABLES
A table which has both PrimaryKey and ForiegnKey in it & ForiegnKey refering the primary key in the same table.
You are going to learn
commands (DDL,DML,DQL,DCL,TCL)
datatypes
constraints
CONSTRAINS
Null
Default
PrimaryKey
UniqueKey
ForiegnKey
Check
Auto Increment
views
operators
query writing
joins
sub query
derived table
Views
Indexes
Stored Procedures
Triggers
Functions
Cursors
