# Facts About Relational Model

1. **Relational Model (RM)** organises the data in the form of relations (tables). 
2. A relational DB consists of **collection of tables, each of which is assigned a unique name**. 
3. A **row in a table** represents **a relationship among a set of values**, and **table is collection of such relationships**. 
4. **Tuple:** A single row of the table representing a single data point / a unique record. 
5. **Columns:** represents the attributes of the relation. Each attribute, there is a permitted value, called domain of the attribute. 
6. **Relation Schema:** defines the design and structure of the relation, contains the name of the relation and all the columns/attributes.
7. Common RM based DBMS systems, aka RDBMS: Oracle, IBM, MySQL, MS Access. 
8. **Degree of table:** number of attributes/columns in a given table/relation. 
9. **Cardinality:** Total no. of tuples in a given relation.
10. **Relational Key:** Set of attributes which can uniquely identify an each tuple. 
11. Important properties of a **Table in Relational Model :**
    1. The name of relation is distinct among all other relation.
    2. The values have to be atomic. Can’t be broken down further.
    3. The name of each attribute/column must be unique.
    4. Each tuple must be unique in a table.
    5. The sequence of row and column has no significance.
    6. Tables must follow integrity constraints - it helps to maintain data consistency across the tables


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