Tag: databases

To solve this question, the user needs to know the function NVL2 in SQL.

The NVL2 function in SQL returns one value if an expression is not null, or another value if it is null. The syntax for the NVL2 function is:

NVL2( expression1, expression2, expression3 )

If expression1 is not null, then NVL2 returns expression2. If expression1 is null, then NVL2 returns expression3.

In this case, expression1 is NULL, so NVL2 will return the value of expression3, which is also NULL.

Therefore, the answer is:

The Answer is: A. NULL

To answer this question, the user needs to know the basics of PL/SQL and how it handles exceptions.

A. When a SELECT statement returns more than one row: This is one of the cases where PL/SQL raises an exception. If a SELECT statement returns more than one row in a context where a single value is expected, such as in an assignment statement or a SELECT INTO statement, then PL/SQL will raise the TOO_MANY_ROWS exception.

B. When a SELECT statement returns no rows: This is another case where PL/SQL raises an exception. If a SELECT statement returns no rows in a context where a single value is expected, such as in an assignment statement or a SELECT INTO statement, then PL/SQL will raise the NO_DATA_FOUND exception.

C. When INTO statement is missing in the SELECT statement: This is not a case where PL/SQL raises an exception. If an INTO statement is missing in a SELECT statement, then a compilation error will occur, but it will not result in an exception at runtime.

D. Both I and II: This option is correct. PL/SQL raises exceptions in both cases where a SELECT statement returns more than one row (TOO_MANY_ROWS) and where a SELECT statement returns no rows (NO_DATA_FOUND).

Therefore, the correct answer is: D.

To solve this question, the user needs to know the basics of SQL SELECT statements and string manipulation functions. The user should be familiar with the INITCAP, TRIM, SUBSTR, and LOWER functions.

Now, let's go through each option and explain why it is right or wrong:

A. SELECT INITCAP(TRIM ('HelloWorld', 1,1)) FROM dual;

This option is incorrect. The TRIM function removes characters from the beginning and end of a string. In this case, the second and third arguments of the TRIM function are incorrect. INITCAP capitalizes the first letter of a string and converts the rest of the string to lowercase. Therefore, this SELECT statement will not return the correct result.

B. SELECT SUBSTR( 'HelloWorld',1) FROM dual;

This option is incorrect. The SUBSTR function returns a substring from a given string. In this case, the function only returns the first character of the string 'HelloWorld'. Therefore, this SELECT statement will not return the correct result.

C. SELECT LOWER(SUBSTR('HelloWorld', 1, 1) FROM dual;

This option is incorrect. The SUBSTR function returns a substring from a given string. In this case, the function only returns the first character of the string 'HelloWorld'. The LOWER function converts the substring to lowercase. Therefore, this SELECT statement will not return the correct result.

D. SELECT LOWER(TRIM ('H' FROM 'HelloWorld')) FROM dual;

This option is correct. The TRIM function removes the character 'H' from the beginning of the string 'HelloWorld'. The LOWER function converts the remaining string to lowercase. Therefore, this SELECT statement will return the correct result.

The Answer is: D