Relationship in DBMS
Relationship এর ধারণা- দুই বা ততোধিক relation /টেবিল/ entity এর মধ্যে সম্পর্ককে relationship বলে । 1. Unary Relationship ( Within the an entity ) 2. Binary relationship ( in between two entities, Student-Teacher ) 3. Ternary Relationship ( in between three entities, Student-Teacher-Book) 4. n-ary relationship ( in Between four or more entities, Student-Teacher-Book-Lab-Game) Type of Binary relationship- 1. One to One(1:1) একটি entity set এর সঙ্গে অন্য আর একটি entity set এর relationship কে One - to - one (1:1) relationship বলা হয় । যেমন- 1 chair : 1 person 1 headmaster : 1 School 2. One to Many or Many to One (1:m or m:1) একটি entity set এর সঙ্গে অন্য একাধিক entity set এর relationship কে One - to - Many (1: n ) relationship বলা হয় । এবং এর বিপরীত দিকের relationship কে Many - to - One relationship বলা হয় । Example- 1 school: Many students 1 room: Many persons Man