To answer this question, we need to analyze each SQL statement and determine whether it will execute successfully or not.

A. SELECT lname, jobid, sal, sal+500 FROM emp; This statement will execute successfully because it selects the lname, jobid, sal columns from the emp table and performs the addition of sal and 500.

B. SELECT lname, jobid, sal FROM emp (sal + 500); This statement will not execute successfully because there is a syntax error. The correct syntax to perform calculations on columns is to use the SELECT statement and specify the operation directly on the column, as shown in option A.

C. SELECT lname, jobid, sal, sal + 500 "Bonus" FROM emp; This statement will execute successfully because it selects the lname, jobid, sal columns from the emp table and performs the addition of sal and 500. It also assigns the alias "Bonus" to the calculated column.

D. SELECT lname, jobid, sal, sal + 500 bonus FROM emp; This statement will not execute successfully because there is a syntax error. The column name "bonus" is not enclosed in quotes or square brackets. To include special characters or spaces in column names, they should be enclosed in quotes or square brackets.

E. SELECT lname || to_char(sal+500) "Employee Bonus" FROM emp; This statement will execute successfully because it concatenates the lname column with the result of sal+500. The to_char function is used to convert the calculated value to a character data type. It also assigns the alias "Employee Bonus" to the calculated column.

F. SELECT lname, sal + 500 Employee Bonus FROM emp; This statement will not execute successfully because there is a syntax error. The column name "Employee Bonus" should be enclosed in quotes or square brackets.

Therefore, the SQL statements that will not execute successfully are B, D, and F.

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• Wrong explanation

To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) var2 NUMBER := 0; - This line is correct. It declares a variable var2 of type NUMBER and initializes it with a value of 0. There is no error in this line.

Option B) INTO var2 - This line is correct. It is part of the SELECT statement and specifies that the result of the SELECT query should be stored in the variable var2. There is no error in this line.

Option C) WHERE name = 'JORDAN'; - This line is correct. It is part of the SELECT statement and specifies the condition for the WHERE clause. It filters the rows based on the value of the name column equal to 'JORDAN'. There is no error in this line.

Option D) var1 :=var2 + 2000; - This line will produce an error. The variable var1 is declared as a constant using the CONSTANT keyword. Constants cannot be assigned new values once they are declared. Therefore, trying to assign a new value to var1 will result in an error.

Option E) There are no errors in this PL/SQL block - This option is incorrect. As explained above, the line var1 :=var2 + 2000; will produce an error. Therefore, there is an error in this PL/SQL block.

The correct answer is D. This line (var1 :=var2 + 2000;) will produce an error because var1 is declared as a constant and cannot be assigned a new value.

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• Wrong explanation