Which of the following is a legal expression in SQL?

Question

A) SELECT NULL FROM EMPLOYEE

B) SELECT NAME FROM EMPLOYEE

C) SELECT NAME FROM EMPLOYEE WHEN SALARY = NULL

D) None of the above

Answer 1

The correct answer to the question “Which of the following is a legal expression in SQL” is option (b). SELECT NAME FROM EMPLOYEE. And all the other option is incorrect. If you wish to learn more about SQL and wish to get certified, then check out the SQL certification course from Intellipaat. Also, watch the following video on SQL Tutorial.

Answer 2

B) SELECT NAME FROM EMPLOYEE.

Answer 3

The legal expression in SQL is option B) SELECT NAME FROM EMPLOYEE. Option A is invalid because NULL cannot be used as a column name. Option C is incorrect due to the incorrect usage of the equals (=) operator with NULL. Therefore, option B is the correct choice, as it retrieves the NAME column from the EMPLOYEE table.

Answer 4

The legal expression in SQL among the options provided is option B) SELECT NAME FROM EMPLOYEE.

Option A) SELECT NULL FROM EMPLOYEE is not a valid expression because NULL is a keyword representing the absence of a value and cannot be used as a column name.

Option C) SELECT NAME FROM EMPLOYEE WHEN SALARY = NULL is also not a valid expression. To compare with NULL, you should use the IS NULL or IS NOT NULL operators instead of the equals (=) operator.

Therefore, option B) SELECT NAME FROM EMPLOYEE is the correct choice as it follows the proper syntax and retrieves the NAME column from the EMPLOYEE table.