PHONE of STUDENT having ROLL_NO 4 is NULL. NULL Values: The value which is not known or unavailable is called NULL value.The column ROLL_NO is extracted from relation STUDENT.

Column: Column represents the set of values for a particular attribute.The STUDENT relation defined above has cardinality 4. Cardinality: The number of tuples in a relation is known as cardinality.The STUDENT relation defined above has degree 5. Degree: The number of attributes in the relation is known as degree of the relation.It can change whenever there is insertion, deletion or updation in the database. Table 1 shows the relation instance of STUDENT at a particular time. Relation Instance: The set of tuples of a relation at a particular instance of time is called as relation instance.The above relation contains 4 tuples, one of which is shown as: Tuple: Each row in the relation is known as tuple.If a schema has more than 1 relation, it is called Relational Schema. STUDENT (ROLL_NO, NAME, ADDRESS, PHONE and AGE) is relation schema for STUDENT. Relation Schema: A relation schema represents name of the relation with its attributes.Attribute: Attributes are the properties that define a relation.Consider a relation STUDENT with attributes ROLL_NO, NAME, ADDRESS, PHONE and AGE shown in Table 1. A relational database stores data in the form of relations (tables). Relational Model represents how data is stored in Relational Databases. Challenges of database security in DBMS.Introduction to TimeStamp and Deadlock Prevention Schemes in DBMS.Graph Based Concurrency Control Protocol in DBMS.Two Phase Locking (2-PL) Concurrency Control Protocol | Set 3.Categories of Two Phase Locking (Strict, Rigorous & Conservative).Lock Based Concurrency Control Protocol in DBMS.Condition of schedules to View-equivalent.Precedence Graph For Testing Conflict Serializability in DBMS.Types of Schedules based Recoverability in DBMS.ISRO CS Syllabus for Scientist/Engineer Exam.

ISRO CS Original Papers and Official Keys.

GATE CS Original Papers and Official Keys.

Relational module in easycatalog