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Which of the following is incorrect SQL?
- a)Select max(marks) from student
- b)Select sum(marks) from student
- c)Select max(marks1, marks2) from student
- d)Select sum(marks1, marks2) from student
Correct answer is option 'D'. Can you explain this answer?
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Which of the following is incorrect SQL?a)Select max(marks) from stud...
Aggregate functions are functions that take a collection (a set or multiset) of values as input and return a single value.
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The input to sum and avg must be a collection of numbers, but the other operators can operate on collections of non-numeric data types, such as strings.
Sum function cannot work on two columns.
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Which of the following is incorrect SQL?a)Select max(marks) from stud...
Incorrect SQL Statement: Select sum(marks1, marks2) from student
Explanation:
The SQL statement mentioned in option 'D' is incorrect. Let's understand why it is incorrect:
1. SELECT Statement:
The SELECT statement is used to retrieve data from one or more tables in a database. It is followed by a list of columns or expressions to be retrieved.
2. SUM Function:
The SUM function is used to calculate the sum of a column's values. It takes a column name as its argument and returns the sum of all the values in that column.
3. MAX Function:
The MAX function is used to retrieve the maximum value from a column. It takes a column name as its argument and returns the maximum value in that column.
4. Incorrect Usage of Functions:
The incorrect SQL statement mentioned in option 'D' is "Select sum(marks1, marks2) from student". This statement tries to calculate the sum of two columns (marks1 and marks2) using the SUM function. However, the SUM function in SQL is designed to work with a single column, not multiple columns.
5. Correct Usage:
To calculate the sum of multiple columns, you need to use the '+' operator to add the values of those columns together. Here's the correct SQL statement to calculate the sum of marks1 and marks2:
SELECT marks1 + marks2 AS total_marks FROM student
This statement will retrieve the sum of marks1 and marks2 as total_marks from the student table.
Conclusion:
In SQL, the correct syntax is crucial for the accurate retrieval and manipulation of data. The incorrect SQL statement mentioned in option 'D' violates the syntax rules of SQL as it tries to use the SUM function with multiple columns. The correct way to calculate the sum of multiple columns is to use the '+' operator to add the values together.
Explanation:
The SQL statement mentioned in option 'D' is incorrect. Let's understand why it is incorrect:
1. SELECT Statement:
The SELECT statement is used to retrieve data from one or more tables in a database. It is followed by a list of columns or expressions to be retrieved.
2. SUM Function:
The SUM function is used to calculate the sum of a column's values. It takes a column name as its argument and returns the sum of all the values in that column.
3. MAX Function:
The MAX function is used to retrieve the maximum value from a column. It takes a column name as its argument and returns the maximum value in that column.
4. Incorrect Usage of Functions:
The incorrect SQL statement mentioned in option 'D' is "Select sum(marks1, marks2) from student". This statement tries to calculate the sum of two columns (marks1 and marks2) using the SUM function. However, the SUM function in SQL is designed to work with a single column, not multiple columns.
5. Correct Usage:
To calculate the sum of multiple columns, you need to use the '+' operator to add the values of those columns together. Here's the correct SQL statement to calculate the sum of marks1 and marks2:
SELECT marks1 + marks2 AS total_marks FROM student
This statement will retrieve the sum of marks1 and marks2 as total_marks from the student table.
Conclusion:
In SQL, the correct syntax is crucial for the accurate retrieval and manipulation of data. The incorrect SQL statement mentioned in option 'D' violates the syntax rules of SQL as it tries to use the SUM function with multiple columns. The correct way to calculate the sum of multiple columns is to use the '+' operator to add the values together.
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Which of the following is incorrect SQL?a)Select max(marks) from studentb)Select sum(marks) from studentc)Select max(marks1, marks2) from studentd)Select sum(marks1, marks2) from studentCorrect answer is option 'D'. Can you explain this answer?
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