Chapter 4, Problem 5RQ

Explanation of Solution

Computed column in SQL:

• User can perform computations using SQL queries.
• A computed column does not occurs in the database however it can be computed by using data present in the existing columns.
• The computations can involve any arithmetic operator.
• Computations can computed by using the arithmetic operator such + (addition), - (subtraction), * (multiplication) and / (division).
  • Then write the computation result into a place of a particular column name.

Example:

The example for using computed column in SQL is given below:

SELECT STUDENT_ID, STUDENT_NAME, MAXIMUM_LIMIT – SCORE FROM STUDENT;

The above query is used to display student id, student name and student credit from “STUDENT” table...

Explanation of Solution

Naming the computed column in SQL:

• User can assign a name to the computation by using below ways:
  • Name the computation with the word “AS”.
  • User desired name.

Example:

The example for naming the computed column in SQL is shown below:

SELECT STUDENT_ID, STUDENT_NAME, MAXIMUM_LIMIT – SCORE AS STUDENT_CREDIT FROM STUDENT;

The above query is used to display student id, student name and student credit from “STUDENT” table...