MCQ IN COMPUTER SCIENCE & ENGINEERING

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COMPUTER SCIENCE AND ENGINEERING

SQL

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In a column named “age", containing values 4, 5, 6, the SQL statement “SELECT SUM(age) FROM students;” will return,
A
3
B
15
C
0
D
1
Explanation: 

Detailed explanation-1: -This function calculates the sum of all the numeric values in a column. Let’s use it to retrieve the sum of all ages in the table: SELECT SUM (age) FROM users; It will return “265”.

Detailed explanation-2: -The SUM() function returns the total sum of a numeric column.

Detailed explanation-3: -We can use the COUNT() function to get the total number of students without going through the entire database ourselves. This returns the total number of rows in the Student table.

Detailed explanation-4: -SELECT COUNT(*) returns the count of all records in the result set regardless of NULL values. SELECT COUNT(attribute) returns the count of records containing non-NULL values of the specified column.

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