The attributes that do not exist in the physical database
Types of Attributes • Simple attribute− Simple attributes are atomic values, which cannot be divided further. For example, a student's phone number is an atomic value of 10 digits. • Composite attribute− Composite attributes are made of more than one simple attribute. For example, a student's complete name may have first_name and last_name. • Derived attribute− Derived attributes are the attributes that do not exist in the physical database, but their values are derived from other attributes present in the database. For example, average_salary in a department should not be saved directly in the database, instead it can be derived. For another example, age can be derived from data_of_birth. • Single-value attribute− Single-value attributes contain single value. For example − Social_Security_Number. • Multi-value attribute− Multi-value attributes may contain more than one values. For example, a person can have more than one phone number, email_address, etc.
Two trains P and Q of lengths 250 m and 400 m, respectively, are running in the same direction on parallel tracks at 90 km/h and 120 km/h, respectively....
A 160 m long train crosses another 320 m long train running in the opposite direction in 12 seconds. If the shorter train crosses a pole in 16 seconds, ...
Train ‘A’ travelling with a speed of 42 km/h can cross a pole in 6 seconds. If the length of train ‘B’ is 10% less than that of train ‘A’ an...
A train crosses a pilar in 20 seconds and a platform of length 300 metres in 25 seconds,then what will the 120% of the length of the train.
The distance covered by a train in (5y – 1) hours is (125y³ – 1) km. The speed of the train is.
Train A running at speed of 99 km/hr crosses a platform having twice the length of train in 18 sec. Train B whose length is 390m crosses same platform i...
Two trains of length 200m and 160m respectively are running on parallel lines of rails. When running in the same direction the faster train passes the s...
Two trains are running on parallel lines in the same direction at the speed of 75 km/h and 39 km/h respectively. The faster train crosses a man in the s...
A train running with a speed of 45 km/hr can cross a pole in 10 seconds and a platform in 20 seconds. Find the length of the platform.
Two trains ‘A’ and ‘B’ started from station ‘P’ and ‘Q’ towards station ‘Q’ and ‘P’ respectively at the same time. When they met...