Paun Mihut Catalin Tema 5

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  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Cuprins: Section 7 ....................................................................................................................................................... 2

    Section 7 Lesson 1 Handling Exceptions ................................................................................................... 2

    Test Quiz: Handling Exceptions ............................................................................................................... 10

    Section 7 Lesson 2 Trapping Oracle Server Exceptions........................................................................... 13

    Test Quiz: Trapping Oracle Server Exceptions ........................................................................................ 24

    Section 7 Lesson 3 Trapping User-Defined Exceptions ........................................................................... 28

    Test Quiz: Trapping User-Defined Exceptions ........................................................................................ 34

    Section 7 Lesson 4 Recognizing the Scope of Exceptions ....................................................................... 37

    Test Quiz: Recognizing the Scope of Exceptions ..................................................................................... 41

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Section 7

    Section 7 Lesson 1 Handling Exceptions

    Vocabulary

    Identify the vocabulary word for each definition below:

    Exception Handler Code that defines the recovery actions to be performed when

    execution-time errors occur.

    Exception Occurs when an error occurs during the execution of a program that

    disrupts the normal operation of the program.

    Exception handling Allows clean separation of the error processing code from the

    executable code so that a program can continue operating in the

    presence of errors.

    Exception propagating The exception reproduces itself in successive enclosing blocks until

    a handler is found or there are no more blocks to search in.

    Try It / Solve It

    1. What happens when Oracle encounters a runtime problem while executing a PL/SQL

    block?

    An exception is raised and the rest of the blocks execution section is not executed.

    2. What do you need to add to your PL/SQL block to address these problems?

    Add an exception section that includes handlers to trap and deal with all possible

    problems.

    3. List three advantages of handling exceptions within a PL/SQL block.

    It can protect the user from frequent repeated errors.

    It can prevent data in the database from being lost or overwritten.

    PL/SQL code is more readable because error-handling routines can be written in the

    same block in which the error occurred.

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    4. Run this PL/SQL code and then answer the questions that follow.

    DECLARE

    v_jobid employees.job_id%TYPE;

    BEGIN

    SELECT job_id

    INTO v_jobid

    FROM employees

    WHERE department_id = 80;

    END;

    A. What happens when you run the block?

    The block fails because there is more than one employee in department 80 and an

    exception (error) is raised.

    B. In your own words, explain what you can do to fix this problem.

    Select a unique column for the WHERE clause (the block could still fail if the unique

    value entered did not exist;

    Write an exception handler to trap the error.

    C. Modify the code to fix the problem. Use a TOO_MANY_ROWS exception handler.

    DECLARE

    v_jobid employees.job_id%TYPE;

    BEGIN

    SELECT job_id

    INTO v_jobid

    FROM employees

    WHERE department_id = 80;

    EXCEPTION

    WHEN TOO_MANY_ROWS THEN

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    DBMS_OUTPUT.PUT_LINE ('Too many rows returned from the query');

    END;

    D. Run your modified code. What happens this time?

    The exception is successfully trapped and the message 'Too many rows returned from

    the query is displayed.

    5. Run the following PL/SQL block, which tries to insert a new row (with department_id =

    50) into the departments table. What happens and why?

    BEGIN

    INSERT INTO departments (department_id, department_name,manager_id, location_id)

    VALUES (50, 'A new department', 100, 1500);

    DBMS_OUTPUT.PUT_LINE('The new department was inserted');

    EXCEPTION

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE ('An exception has occurred.');

    END;

    The INSERT statement failed because department_id 50 already exists and department_id

    is a unique column. The rest of the executable section was skipped, therefore the message

    The new department was inserted was not displayed. The WHEN OTHERS exception

    handler was executed.

    6. Enter the following PL/SQL block, which tries to SELECT all the employees in a specific

    department. Run it three times, using department_ids 10, 20, and 30. What happens and

    why?

    DECLARE

    v_employee_id employees.employee_id%TYPE;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    v_last_name employees.last_name%TYPE;

    BEGIN

    SELECT employee_id, last_name INTO v_employee_id, v_last_name

    FROM employees

    WHERE department_id = ;

    DBMS_OUTPUT.PUT_LINE('The SELECT was successful');

    EXCEPTION

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('An exception has occurred');

    END;

    Using department_id = 10 is successful because there is exactly one employee in that

    department, therefore the SELECT returned exactly one row.

    Using department_id 20 failed because there is more than one employee in that

    department.

    Using department_id 30 failed because there are no employees in that department.

    7. Modify your code from question 6 to add two more exception handlers to trap the

    possible exceptions individually. Use NO_DATA_FOUND and TOO_MANY_ROWS. Re-

    run the block three times, using 10, 20, and 30 as before. Observe the message displayed in

    each case.

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    DECLARE

    v_employee_id employees.employee_id%TYPE;

    v_last_name employees.last_name%TYPE;

    BEGIN

    SELECT employee_id, last_name INTO v_employee_id, v_last_name

    FROM employees

    WHERE department_id = ;

    DBMS_OUTPUT.PUT_LINE('The SELECT was successful');

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('No rows were selected');

    WHEN TOO_MANY_ROWS THEN

    DBMS_OUTPUT.PUT_LINE('More than one row was selected');

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('An exception has occurred');

    END;

    Pentru valoarea 10 :

    Pentru valoarea 20:

    Pentru valoarea 30:

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    8. List three guidelines for trapping exceptions.

    Always add exception handlers whenever there is a possibility of an error occurring.

    Handle named exceptions whenever possible, instead of using OTHERS in exception

    handlers.

    Test your code with different combinations of bad data to see what potential errors

    arise.

    Write out debugging information in your exception handlers.

    Carefully consider whether each exception handler should commit the transaction, roll

    it back, or let it continue.

    9. Enter and run the following PL/SQL block. Explain the output. Note: the WHEN

    OTHERS handler successfully handles any type of exception which occurs.

    DECLARE

    v_number NUMBER(2);

    BEGIN

    v_number := 9999;

    EXCEPTION

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('An exception has occurred');

    EN An exception has occurred because the 4-digit value 9999 is too large to be assigned to a

    NUMBER(2) variable. The blocks exception section has handled the exception successfully

    and displayed An exception has occurred. The exception has NOT been propagated back

    to the calling environment (Application Express) which therefore reports Statement

    Processed, meaning: success.

    10. Modify the block in question 9 to omit the exception handler, then re-run the block.

    Explain the output.

    DECLARE

    v_number NUMBER(2);

    BEGIN

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    v_number := 9999;

    END;

    The block does not handle the exception, which therefore propagates back to Application

    Express. Application Express displays an ORA-06502: PL/SQL: numeric or value error: number

    precision too large.

    11. Enter and run the following code and explain the output.

    DECLARE

    v_number NUMBER(4);

    BEGIN

    v_number := 1234;

    DECLARE

    v_number NUMBER(4);

    BEGIN

    v_number := 5678;

    v_number := 'A character string';

    END;

    EXCEPTION

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('An exception has occurred');

    DBMS_OUTPUT.PUT_LINE('The number is: '||v_number);

    END;

    The inner blocks attempt to assign a character string to a NUMBER variable causes an

    exception. The exception is not handled in the inner block, which therefore propagates the

    exception to the outer block. The outer block successfully handles the exception.

    The number 1234 (not 5678) is displayed because the inner blocks v_number is out of

    scope in the outer block.

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Test Quiz: Handling Exceptions Section 1

    (Answer all questions in this section)

    1. Which of the following is NOT an advantage of including an exception handler in a PL/SQL block? Mark for Review

    (1) Points

    Avoids costly and time-consuming correction of mistakes

    Prevents errors from being propagated back to the calling environment

    Prevents errors from occurring (*)

    Code is more readable because error-handling routines can be written in the same block in which the error occurred

    Correct

    2. Which of the following best describes a PL/SQL exception? Mark for Review

    (1) Points

    A user enters an invalid password while trying to log on to the database.

    An error occurs during the execution of the block, which disrupts the normal operation of the program. (*)

    The programmer forgets to declare a cursor while writing the PL/SQL code.

    A compile-time error occurs because the PL/SQL code references a non-existent table.

    Correct

    3. Which of these exceptions can be handled by an EXCEPTION section in a PL/SQL block? Mark for Review

    (1) Points

    An attempt is made to divide by zero

    A SELECT statement returns no rows

    Any other kind of exception that can occur within the block

    All of the above (*)

    None of the above

    Correct

    4. Only one exception at a time can be raised during one execution of a PL/SQL block. True or False? Mark for Review

    (1) Points

    True (*)

    False

    Correct

    5. Which of the following EXCEPTION sections is constructed correctly? (Choose three.) Mark for Review

    (1) Points

    (Choose all correct answers)

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    EXCEPTION WHEN NO_DATA_FOUND THEN statement_1; WHEN OTHERS THEN statement_2; END;

    (*)

    EXCEPTION WHEN NO_DATA_FOUND THEN statement_1; WHEN NO_DATA_FOUND THEN statement_2; WHEN OTHERS THEN statement_3; END;

    EXCEPTION WHEN OTHERS THEN statement_1; END;

    (*)

    EXCEPTION WHEN OTHERS THEN statement_1; WHEN NO_DATA_FOUND THEN statement_2; END;

    EXCEPTION WHEN TOO_MANY_ROWS THEN statement_1; END;

    (*)

    Incorrect. Refer to Section 7 Lesson 1.

    6. The following EXCEPTION section is constructed correctly. True or False?

    EXCEPTION WHEN ZERO_DIVIDE OR TOO_MANY_ROWS OR NO_DATA_FOUND THEN statement_1; statement_2; WHEN OTHERS THEN statement_3; END;

    Mark for Review (1) Points

    True (*)

    False

    Correct

    7. Which of the following are NOT good practice guidelines for exception handling? (Choose two.) Mark for Review

    (1) Points

    (Choose all correct answers)

    Handle specific named exceptions where possible, instead of relying on WHEN OTHERS.

    Test your code with different combinations of data to see what potential errors can happen.

    Use an exception handler whenever there is any possibility of an error occurring.

    Allow exceptions to propagate back to the calling environment. (*)

    Include a WHEN OTHERS handler as the first handler in the exception section. (*)

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Correct

    8. Examine the following code. Why does this exception handler not follow good practice guidelines? (Choose two.)

    DECLARE v_dept_name departments.department_name%TYPE; BEGIN SELECT department_name INTO v_dept_name FROM departments WHERE department_id = 75; EXCEPTION WHEN OTHERS THEN DBMS_OUTPUT.PUT_LINE('A select returned more than one row');

    END;

    Mark for Review (1) Points

    (Choose all correct answers)

    The exception handler should COMMIT the transaction.

    The exception handler should test for the named exception NO_DATA_FOUND. (*)

    You should not use DBMS_OUTPUT.PUT_LINE in an exception handler.

    The exception section should include a WHEN TOO_MANY_ROWS exception handler. (*)

    department_id 75 does not exist in the departments table.

    Correct

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Section 7 Lesson 2 Trapping Oracle Server Exceptions

    Vocabulary

    Identify the vocabulary word for each definition below:

    Predefined Oracle Server

    Errors

    Each of these has a predefined name. For example, if the error ORA-

    01403 occurs when no rows are retrieved from the database in a

    SELECT statement, then PL/SQL raises the predefined exception-

    name NO_DATA_FOUND.

    PRAGMA

    EXCEPTION_INIT

    Tells the compiler to associate an exception name with an Oracle

    error number. That allows you to refer to any Oracle Server

    exception by name and to write a specific handler for it.

    SQLERRM Returns character data containing the message associated with the

    error number

    Non-predefined Oracle

    Server Errors

    Each of these has a standard Oracle error number (ORA-nnnnn) and

    error message, but not a predefined name. We declare our own

    names for these so that we can reference these names in the

    exception section.

    SQLCODE Returns the numeric value for the error code (You can assign it to a

    NUMBER variable.)

    Try It / Solve It

    1. What are the three types of exceptions that can be handled in a PL/SQL block?

    predefined Oracle errors

    non-predefined Oracle errors

    user-defined errors

    2. What is the difference in how each of these three types of exceptions is handled in the

    PL/SQL block?

    predefined: Oracle has assigned a name to about 20 of the most common errors. We

    reference the predefined names directly in the exception section of the block;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    non-predefined: these errors do not have names and so a name must be defined in the

    declare section and associated with an Oracle error number; the name is then used in

    the exception section;

    user defined: these are unknown to Oracle and must be named in the declare section,

    raised explicitly in the executable section and then the name used in the exception

    section

    3. Enter and run the following PL/SQL block. Look at the output and answer the following

    questions:

    DECLARE

    v_number NUMBER(6,2) := 100;

    v_region_id wf_world_regions.region_id%TYPE;

    v_region_name wf_world_regions.region_name%TYPE;

    BEGIN

    SELECT region_id, region_name INTO v_region_id, v_region_name

    FROM wf_world_regions

    WHERE region_id = 1;

    DBMS_OUTPUT.PUT_LINE('Region: ' || v_region_id ||' is: ' || v_region_name);

    v_number := v_number / 0;

    END;

    A. What error message is displayed and why ?

    Because region_id = 1 does not exist, the predefined exception NO_DATA_FOUND is

    raised but is not trapped within the block. The exception is propagated back to the

    calling environment (Application Express) which displays ORA-01403: no data found

    B. Modify the block to handle this exception and re-run your code. Now what happens and

    why?

    DECLARE

    v_number NUMBER(6,2) := 100;

    v_region_id wf_world_regions.region_id%TYPE;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    v_region_name wf_world_regions.region_name%TYPE;

    BEGIN

    SELECT region_id, region_name INTO v_region_id, v_region_name

    FROM wf_world_regions

    WHERE region_id = 1;

    DBMS_OUTPUT.PUT_LINE('Region: ' || v_region_id ||' is: ' || v_region_name);

    v_number := v_number / 0;

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('Select returned no rows');

    END;

    Now the exception is successfully trapped and the corresponding exception handler is

    executed.

    C. Modify the block again to change the WHERE clause to region_id = 29. Re-run the

    block. Now what happens and why?

    Now the SELECT executes successfully because region_id 29 exists. Block execution

    continues, but the next statement attempts to divide 100 by zero and raises an

    unhandled ORA-01476 exception.

    D. Modify the block again to handle the latest exception and re-run your code.

    DECLARE

    v_number NUMBER(6,2) := 100;

    v_region_id wf_world_regions.region_id%TYPE;

    v_region_name wf_world_regions.region_name%TYPE;

    BEGIN

    SELECT region_id, region_name INTO v_region_id, v_region_name

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    FROM wf_world_regions

    WHERE region_id = 29;

    DBMS_OUTPUT.PUT_LINE('Region: ' || v_region_id ||' is: ' || v_region_name);

    v_number := v_number / 0;

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('Select returned no rows');

    WHEN ZERO_DIVIDE THEN

    DBMS_OUTPUT.PUT_LINE('Attempt to divide by zero');

    END;

    4. Enter and run the following PL/SQL block. Look at the output and answer the following

    questions:

    DECLARE

    CURSOR regions_curs IS

    SELECT * FROM wf_world_regions

    WHERE region_id < 20

    ORDER BY region_id;

    regions_rec regions_curs%ROWTYPE;

    v_count NUMBER(6);

    BEGIN

    LOOP

    FETCH regions_curs INTO regions_rec;

    EXIT WHEN regions_curs%NOTFOUND;

    DBMS_OUTPUT.PUT_LINE('Region: '|| regions_rec.region_id ||' Name: ' ||

    regions_rec.region_name);

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    END LOOP;

    CLOSE regions_curs;

    SELECT COUNT(*) INTO v_count

    FROM wf_world_regions

    WHERE region_id = 1;

    DBMS_OUTPUT.PUT_LINE('The number of regions is: ' || v_count);

    END;

    A. What happens and why ?

    The first FETCH fails because the cursor has not been opened. The predefined

    exception INVALID_CURSOR is raised but is not trapped within the block.

    B. Modify the block to handle the exception and re-run your code.

    DECLARE

    CURSOR regions_curs IS

    SELECT * FROM wf_world_regions

    WHERE region_id < 20

    ORDER BY region_id;

    regions_rec regions_curs%ROWTYPE;

    v_count NUMBER(6);

    BEGIN

    LOOP

    FETCH regions_curs INTO regions_rec;

    EXIT WHEN regions_curs%NOTFOUND;

    DBMS_OUTPUT.PUT_LINE('Region: '|| regions_rec.region_id ||' Name: ' ||

    regions_rec.region_name);

    END LOOP;

    CLOSE regions_curs;

    SELECT COUNT(*) INTO v_count

    FROM wf_world_regions

    WHERE region_id = 1;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    DBMS_OUTPUT.PUT_LINE('The number of regions is: ' || v_count);

    EXCEPTION

    WHEN INVALID_CURSOR THEN

    DBMS_OUTPUT.PUT_LINE('Attempt to fetch from an unopenedcursor ');

    END;

    C. Modify the block again to add an OPEN statement for the cursor, and re-run your code.

    Now what happens and why? Remember that region_id = 1 does not exist.

    DECLARE

    CURSOR regions_curs IS

    SELECT * FROM wf_world_regions

    WHERE region_id < 20

    ORDER BY region_id;

    regions_rec regions_curs%ROWTYPE;

    v_count NUMBER(6);

    BEGIN

    OPEN regions_curs;

    LOOP

    FETCH regions_curs INTO regions_rec;

    EXIT WHEN regions_curs%NOTFOUND;

    DBMS_OUTPUT.PUT_LINE('Region: '|| regions_rec.region_id || ' Name: ' ||

    regions_rec.region_name);

    END LOOP;

    CLOSE regions_curs;

    SELECT COUNT(*) INTO v_count

    FROM wf_world_regions

    WHERE region_id = 1;

    DBMS_OUTPUT.PUT_LINE('The number of regions is: ' || v_count);

    EXCEPTION

    WHEN INVALID_CURSOR THEN

    DBMS_OUTPUT.PUT_LINE('Attempt to fetch from an unopened cursor');

    END;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    The cursor loop now works fine, so execution continues to the SELECT COUNT(*)

    Some students may expect this to fail because region_id 1 does not exist. But a SELECT

    COUNT(*) (unlike SELECT * ) always returns exactly one row, in this case with a

    value of 0.

    5. Oracle Server Errors:

    A. Add an exception handler to the following code to trap the following predefined Oracle

    Server errors: NO_DATA_FOUND, TOO_MANY_ROWS, and DUP_VAL_ON_INDEX.

    DECLARE

    v_language_id wf_languages.language_id%TYPE;

    v_language_name wf_languages.language_name%TYPE;

    BEGIN

    SELECT language_id, language_name

    INTO v_language_id, v_language_name

    FROM wf_languages

    WHERE LOWER(language_name) LIKE ''; -- for example 'ab%'

    INSERT INTO wf_languages(language_id, language_name)

    VALUES(80, null);

    END;

    Add the following exception section:

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('No rows were found');

    WHEN TOO_MANY_ROWS THEN

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    DBMS_OUTPUT.PUT_LINE('More than one row was found');

    WHEN DUP_VAL_ON_INDEX THEN

    DBMS_OUTPUT.PUT_LINE('This language id already exists');

    B. Test your block twice using each of the following language substrings: ba, ce. There are

    several language_names beginning with Ba but none beginning with Ce.

    Pentru ba%:

    Pentru ce%:

    C. Now test your block a third time using substring: al. There is exactly one

    language_name beginning with Al. Note that language_id 80 (Arabic) already exists.

    Explain the output.

    The SELECT succeeds but the INSERT fails with an ORA-01400 exception because

    language_name cannot be null.

    D. Now (keeping the substring as al) add a non_predefined exception handler to trap the

    ORA-01400 exception. Name your exception e_null_not_allowed. Rerun the code and

    observe the results.

    DECLARE

    v_language_id wf_languages.language_id%TYPE;

    v_language_name wf_languages.language_name%TYPE;

    e_null_not_allowed EXCEPTION;

    PRAGMA EXCEPTION_INIT(e_null_not_allowed, -01400);

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    BEGIN

    SELECT language_id, language_name

    INTO v_language_id, v_language_name

    FROM wf_languages

    WHERE lower(language_name) LIKE al%;

    INSERT INTO wf_languages(language_id, language_name)

    VALUES(80, null);

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('No rows were found');

    WHEN TOO_MANY_ROWS THEN

    DBMS_OUTPUT.PUT_LINE('More than one row was found');

    WHEN DUP_VAL_ON_INDEX THEN

    DBMS_OUTPUT.PUT_LINE('This language id already exists');

    WHEN e_null_not_allowed THEN

    DBMS_OUTPUT.PUT_LINE('Language name cannot be null');

    END;

    Extension exercise

    1. In preparation for this exercise, run the following SQL statement to create an error-

    logging table:

    CREATE TABLE error_log (who VARCHAR2(30),

    when DATE,

    error_code NUMBER(6),

    error_message VARCHAR2(255));

    Modify your PL/SQL block from question 5 to remove the four explicit exception handlers,

    replacing them with a single WHEN OTHERS handler. The handler should INSERT a row into

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    the error_log table each time an exception is raised and handled. The row should consist of the

    Oracle username (who), when the error was raised (when), and the SQLCODE and SQLERRM

    of the exception. Test your block several times, with different data values to raise each of the

    four kinds of exceptions handled in the block. Finally, SELECT from the error-logging table to

    check that the rows have been inserted.

    DECLARE

    v_language_id wf_languages.language_id%TYPE;

    v_language_name wf_languages.language_name%TYPE;

    v_sqlcode NUMBER(5);

    v_sqlerrm VARCHAR2(255);

    BEGIN

    SELECT language_id, language_name

    INTO v_language_id, v_language_name

    FROM wf_languages

    WHERE lower(language_name) LIKE '';

    INSERT INTO wf_languages(language_id, language_name)

    VALUES(80, null);

    EXCEPTION

    WHEN OTHERS THEN

    v_sqlcode := SQLCODE;

    v_sqlerrm := SQLERRM;

    INSERT INTO error_log(who, when, error_code, error_message)

    VALUES(USER, SYSDATE, v_sqlcode, v_sqlerrm);

    END;

    SELECT * FROM error_log;

    Dupa mai multe verificari de coduri am mai facut un SELECT:

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Test Quiz: Trapping Oracle Server Exceptions Section 1

    (Answer all questions in this section)

    1. Which of the following is NOT a predefined Oracle Server error? Mark for Review

    (1) Points

    TOO_MANY_ROWS

    ZERO_DIVIDE

    DUP_VAL_ON_INDEX

    NO_DATA_FOUND

    e_sal_too_high EXCEPTION; (*)

    Correct

    2. Which of the following best describes a predefined Oracle Server error? Mark for Review

    (1) Points

    Is not raised automatically but must be declared and raised explicitly by the PL/SQL programmer

    Is associated with an Oracle error number using PRAGMA EXCEPTION_INIT

    Has a standard Oracle error number but must be declared and named by the PL/SQL programmer

    Has a standard Oracle error number and a standard name which can be referenced in the EXCEPTION section (*)

    Correct

    3. Which kind of error can NOT be handled by PL/SQL? Mark for Review

    (1) Points

    Non-predefined Oracle Server errors

    Syntax errors (*)

    Predefined Oracle Server errors

    User-defined errors

    Correct

    4. Examine the following code. At Line A, you want to raise an exception if the employee's manager_id is null. What kind of exception is this?

    DECLARE v_mgr_id employees.manager_id%TYPE; BEGIN SELECT manager_id INTO v_mgr_id FROM employees WHERE employee_id = 100; IF v_mgr_id IS NULL THEN -- Line A END IF; ...

    Mark for Review (1) Points

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    A NO_DATA_FOUND exception

    A non-predefined Oracle server exception

    A constraint violation

    A user-defined exception (*)

    A predefined Oracle Server exception

    Correct

    5. How would you trap Oracle Server exception ORA-01403: no data found? Mark for Review

    (1) Points

    WHEN NO_DATA_FOUND THEN ... (*)

    WHEN SQL%ROWCOUNT=0 THEN ...

    WHEN NO DATA FOUND THEN ...

    WHEN ORA-01403 THEN ...

    Correct

    6. No employees exist whose salary is less than 2000. Which exception handlers would successfully trap the exception that will be raised when the following code is executed? (Choose two.)

    DECLARE v_mynum NUMBER := 10; v_count NUMBER; BEGIN SELECT COUNT(*) INTO v_count FROM employees WHERE salary < 2000; v_mynum := v_mynum / v_count; EXCEPTION ... END;

    Mark for Review (1) Points

    (Choose all correct answers)

    NO_DATA_FOUND

    ZERO_DIVIDE (*)

    SQL%ROWCOUNT = 0

    OTHER

    OTHERS (*)

    Correct

    7. What is the correct syntax to associate an exception named EXCEPNAME with the non-predefined Oracle Server error ORA-02292? Mark for Review

    (1) Points

    SQLCODE (-2292, excepname);

    RAISE_APPLICATION_ERROR (-2292, excepname);

    PRAGMA EXCEPTION_INIT (excepname, -2292) (*)

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    WHEN (-2292, excepname) THEN

    Correct

    8. An ORA-1400 exception is raised if an attempt is made to insert a null value into a NOT NULL column. DEPARTMENT_ID is the primary key of the DEPARTMENTS table. What will happen when the following code is executed?

    DECLARE e_not_null EXCEPTION; BEGIN PRAGMA EXCEPTION_INIT(e_not_null, -1400); INSERT INTO departments (department_id, department_name)

    VALUES(null, 'Marketing'); EXCEPTION WHEN e_not_null THEN DBMS_OUTPUT.PUT_LINE('Cannot be null'); END;

    Mark for Review (1) Points

    The code will not execute because the syntax of PRAGMA EXCEPTION_INIT is wrong.

    The code will not execute because the syntax of the INSERT statement is wrong.

    The exception will be raised and "Cannot be null" will be displayed.

    The code will not execute because PRAGMA EXCEPTION_INIT must be coded in the DECLARE section. (*)

    Correct

    9. Examine the following code. The UPDATE statement will raise an ORA-02291 exception.

    BEGIN UPDATE employees SET department_id = 45; EXCEPTION WHEN OTHERS THEN INSERT INTO error_log_table VALUES (SQLCODE); END;

    What will happen when this code is executed?

    Mark for Review (1) Points

    The code will fail because we cannot use functions like SQLCODE directly in a SQL statement. (*)

    The code will fail because we access error message numbers by using SQLERRNUM, not SQLCODE.

    The code will fail because SQLCODE has not been declared.

    The code will execute and insert error number 02291 into error_log_table.

    Correct

    10. Which type of exception MUST be explicitly raised by the PL/SQL programmer? Mark for Review

    (1) Points

    User-defined exceptions (*)

    Predefined Oracle server errors such as TOO_MANY_ROWS

    Non-predefined Oracle server errors such as ORA-01203

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    All of the above

    Correct

    11. A PL/SQL block executes and an Oracle Server exception is raised. Which of the following contains the text message associated with the exception? Mark for Review

    (1) Points

    SQLERRM (*)

    SQL_MESSAGE_TEXT

    SQLCODE

    SQL%MESSAGE

    Correct

    12. Which one of the following events would implicitly raise an exception? Mark for Review

    (1) Points

    A database constraint is violated. (*)

    An UPDATE statement modifies no rows.

    A SELECT statement returns exactly one row.

    The PL/SQL programmer mis-spells the word BEGIN as BEGAN.

    Correct

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Section 7 Lesson 3 Trapping User-Defined Exceptions

    Vocabulary

    Identify the vocabulary word for each definition below:

    RAISE_APPLICATIO

    N_ERROR

    A procedure used to return user-defined error messages from

    stored subprograms.

    RAISE Use this statement to raise a named exception.

    user-defined errors These errors are not automatically rased by the Oracle Server, but

    are defined by the programmer and are specific to the

    programmer's code.

    Try It / Solve It

    All the questions in this exercise use a copy of the employees table. Create this copy by running

    the following SQL statement:

    CREATE TABLE excep_emps AS SELECT * FROM employees;

    1. Create a PL/SQL block that updates the salary of every employee to a new value of

    10000 in a chosen department. Include a user-defined exception handler that handles the

    condition where no rows are updated and displays a custom message. Also include an

    exception handler that will trap any other possible error condition and display the

    corresponding SQLCODE and SQLERRM. Test your code three times, using

    department_ids 20, 30, and 40.

    DECLARE

    e_no_rows_updated EXCEPTION;

    BEGIN

    UPDATE excep_emps

    SET salary = 10000

    WHERE department_id = ;

    IF SQL%NOTFOUND THEN -- sau putem spune: IF SQL%ROWCOUNT = 0

    RAISE e_no_rows_updated;

    END IF;

    EXCEPTION

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    WHEN e_no_rows_updated THEN

    DBMS_OUTPUT.PUT_LINE ( 'There are no employees in that department.');

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('An error has occurred:'||SQLCODE || '-' || SQLERRM);

    END;

    Pentru department_id = 20:

    Pentru department_id = 30:

    Pentru department_id = 40:

    2. Modify your code from question 2 to handle the condition where no rows are updated

    using RAISE_APPLICATION_ERROR procedure in the exception section. Use an error

    number of 20202. Test your code again using department_id 40 and check that the 20202

    error is displayed.

    DECLARE

    e_no_rows_updated EXCEPTION;

    BEGIN

    UPDATE excep_emps

    SET salary = 10000

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    WHERE department_id = 40;

    IF SQL%NOTFOUND THEN

    RAISE e_no_rows_updated;

    END IF;

    EXCEPTION

    WHEN e_no_rows_updated THEN

    RAISE_APPLICATION_ERROR(-20202,'There are no employees in that department');

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('An error has occurred: '||SQLCODE || '-' || SQLERRM);

    END;

    3. Modify your code from question 3 to use RAISE_APPLICATION_ERROR in the

    executable section instead of the exception section. Test your code again using

    department_id 40.

    DECLARE

    _no_rows_updated EXCEPTION;

    BEGIN

    UPDATE excep_emps

    SET salary = 10000

    WHERE department_id = 40;

    IF SQL%NOTFOUND THEN

    RAISE_APPLICATION_ERROR(-20202,'There are no employees in that department');

    END IF;

    END;

    4. Before starting this question, disable Autocommit in Application Express.

    A. Enter and run the following PL/SQL block using department_id = 40, and explain the

    output.

    DECLARE

    v_dept_id excep_emps.department_id%TYPE;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    v_count NUMBER;

    BEGIN

    v_dept_id := 40;

    SELECT COUNT(*) INTO v_count

    FROM excep_emps

    WHERE department_id = v_dept_id;

    DBMS_OUTPUT.PUT_LINE('There are ' || v_count || ' employees');

    DELETE FROM excep_emps

    WHERE department_id = v_dept_id;

    DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT ||' employees were deleted');

    ROLLBACK;

    END;

    Both the SELECT and the DELETE execute successfully (no exceptions are raised) although

    there are no employees in department 40.

    B. Modify your block to include two user-defined exception handlers, one to test whether

    SELECT returns a value of 0, and the other to test if no rows were DELETEd. Declare the

    exceptions and RAISE them explicitly before trapping them in the exception section. Do

    NOT use RAISE_APPLICATION_ERROR. Test your modified block using

    department_id 40.

    DECLARE

    v_dept_id excep_emps.department_id%TYPE;

    v_count NUMBER;

    e_no_emps_in_dept EXCEPTION;

    e_no_rows_deleted EXCEPTION;

    BEGIN

    v_dept_id := 40;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    SELECT COUNT(*) INTO v_count

    FROM excep_emps

    WHERE department_id = v_dept_id;

    IF v_count = 0 THEN

    RAISE e_no_emps_in_dept;

    END IF;

    DBMS_OUTPUT.PUT_LINE('There are ' || v_count || ' employees');

    DELETE FROM excep_emps

    WHERE department_id = v_dept_id;

    IF SQL%NOTFOUND THEN -- or IF SQL%ROWCOUNT = 0 THEN

    RAISE e_no_rows_deleted;

    END IF;

    DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT ||' employees were deleted');

    ROLLBACK;

    EXCEPTION

    WHEN e_no_emps_in_dept THEN

    DBMS_OUTPUT.PUT_LINE('This department has no employees');

    WHEN e_no_rows_deleted THEN

    DBMS_OUTPUT.PUT_LINE('No employees were deleted');

    END;

    C. Modify your block again to use RAISE_APPLICATION_ERROR in the executable

    section. Use error numbers 20203 and 20204. Test your modified block using

    department_id 40.

    DECLARE

    v_dept_id excep_emps.department_id%TYPE;

    v_count NUMBER;

    BEGIN

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    v_dept_id := 40;

    SELECT COUNT(*) INTO v_count

    FROM excep_emps

    WHERE department_id = v_dept_id;

    IF v_count = 0 THEN

    RAISE_APPLICATION_ERROR(-20203,'This department has no employees');

    END IF;

    DBMS_OUTPUT.PUT_LINE('There are ' || v_count || ' employees');

    DELETE FROM excep_emps

    WHERE department_id = v_dept_id;

    IF SQL%NOTFOUND THEN -- sau IF SQL%ROWCOUNT = 0 THEN

    RAISE_APPLICATION_ERROR(-20204,'No employees were deleted');

    END IF;

    DBMS_OUTPUT.PUT_LINE(SQL%ROWCOUNT ||' employees were deleted');

    ROLLBACK;

    END;

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Test Quiz: Trapping User-Defined Exceptions Section 1

    (Answer all questions in this section)

    1. What is a user-defined exception? Mark for Review

    (1) Points

    A predefined Oracle server exception such as NO_DATA_FOUND.

    An exception which has a predefined Oracle error number but no predefined name.

    An exception which is not raised automatically by the Oracle server, but must be

    declared and raised explicitly by the PL/SQL programmer. (*)

    An exception handler which the user (the programmer) includes in the EXCEPTION section.

    Correct

    2. What is the datatype of a user-defined exception? Mark for Review

    (1) Points

    BOOLEAN

    VARCHAR2

    EXCEPTION (*)

    NUMBER

    None of the above

    Correct

    3. What is wrong with the following code?

    BEGIN UPDATE employees SET salary = 20000 WHERE job_id = 'CLERK'; IF SQL%ROWCOUNT = 0 THEN RAISE NO_DATA_FOUND; -- Line A END IF; EXCEPTION WHEN NO_DATA_FOUND THEN DBMS_OUTPUT.PUT_LINE('No employee was updated'); END;

    Mark for Review (1) Points

    Line A should be: HANDLE NO_DATA_FOUND

    You cannot use SQL%ROWCOUNT in conditional control statements such as IF or CASE.

    Nothing is wrong; the code will execute correctly. (*)

    NO_DATA_FOUND has not been DECLAREd.

    You cannot explicitly raise predefined Oracle Server errors such as NO_DATA_FOUND.

    Correct

    4. What will be displayed when the following code is executed? Mark for Review

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    DECLARE e_myexcep EXCEPTION; BEGIN DBMS_OUTPUT.PUT_LINE('Message 1'); RAISE e_myexcep; DBMS_OUTPUT.PUT_LINE('Message 2'); EXCEPTION WHEN e_myexcep THEN DBMS_OUTPUT.PUT_LINE('Message 3'); RAISE e_myexcep; DBMS_OUTPUT.PUT_LINE('Message 4'); END;

    (1) Points

    The code will not execute because it contains at least one syntax error.

    The code will execute but will return an unhandled exception to the calling environment.

    (*)

    Message 1 Message 2 Message 3 Message 4

    Message 1 Message 3 Message 4

    Message 1 Message 3

    Correct

    5. The following line of code is correct. True or False? RAISE_APPLICATION_ERROR(-21001,'My error message'); Mark for Review

    (1) Points

    True

    False (*)

    Correct

    6. How are user-defined exceptions raised ? Mark for Review

    (1) Points

    By PRAGMA EXCEPTION_INIT

    By DECLARE e_my_excep EXCEPTION;

    By RAISE exception_name; (*)

    None of the above. They are raised automatically by the Oracle server.

    Correct

    7. The following three steps must be performed to use a user-defined exception: - Raise the exception - Handle the exception - Declare the exception In what sequence must these steps be performed?

    Mark for Review (1) Points

    The steps can be performed in any order.

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Declare, Raise, Handle (*)

    Handle, Raise, Declare

    Raise, Handle, Declare

    Correct

    8. You want to display your own error message to the user. What is the correct syntax to do this? Mark for Review

    (1) Points

    RAISE application_error;

    RAISE_APPLICATION_ERROR('My own message', -20001);

    RAISE_APPLICATION_ERROR(20001, 'My own message');

    RAISE_APPLICATION_ERROR (-20001, 'My own message'); (*)

    Correct

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Section 7 Lesson 4 Recognizing the Scope of Exceptions

    Vocabulary

    Identify the vocabulary word for each definition below:

    Propogation The inner block terminates unsuccessfully, and PL/SQL passes the

    exception to the outer block.

    Exception scope The portion of a program in which the exception is declared and is

    accessible.

    Try It / Solve It

    1. Enter and run the following code twice, once for each of the two country_ids 5 (which

    does not exist) and 672 (Antarctica, which does exist but has no currency).

    DECLARE

    v_country_name wf_countries.country_name%TYPE;

    v_currency_code wf_countries.currency_code%TYPE;

    BEGIN

    DECLARE

    e_no_currency EXCEPTION;

    BEGIN

    SELECT country_name, currency_code

    INTO v_country_name, v_currency_code

    FROM wf_countries

    WHERE country_id = 5; -- repeat with 672

    IF v_currency_code = 'NONE' THEN

    RAISE e_no_currency;

    END IF;

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('This country does not exist');

    WHEN e_no_currency THEN

    DBMS_OUTPUT.PUT_LINE('This country exists but has no currency');

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    END;

    EXCEPTION

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('Another type of error occurred');

    END;

    A. Explain the output. Save your code.

    Country_id 5 raises NO_DATA_FOUND and This country does not exist is displayed.

    Country_id 672 raises e_no_currency and This country exists but has no currency is displayed.

    B. Modify the code to move the two exception handlers to the outer block. Leave the

    declaration of e_no_currency in the inner block. Execute twice, again using country_ids 5

    and 672. Now what happens and why? Save your code.

    DECLARE

    v_country_name wf_countries.country_name%TYPE;

    v_currency_code wf_countries.currency_code%TYPE;

    BEGIN

    DECLARE

    e_no_currency EXCEPTION;

    BEGIN

    SELECT country_name, currency_code

    INTO v_country_name, v_currency_code

    FROM wf_countries

    WHERE country_id = 5; -- repeat with 672

    IF v_currency_code = 'NONE' THEN

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    RAISE e_no_currency;

    END IF;

    END;

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('This country does not exist');

    WHEN e_no_currency THEN

    DBMS_OUTPUT.PUT_LINE('This country exists but has no currency');

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('Another type of error occurred');

    END;

    In both executions, a PLS-00201 Identifier E_NO_CURRENCY must be declared error

    occurs, because e_no_currency was declared in the inner block and is therefore out of

    scope in the outer block. We would expect this for country_id 672, but what about

    country_id 5, which should raise a NO_DATA_FOUND? PLS-00201 is a compile-time

    error. This shows that PL/SQL checks the scope of variables when compiling the code, not

    when executing it. If invalid scope is detected, the code is not executed at all.

    C. Modify the code again to move the declaration of e_no_currency to the outer block. Re-

    execute again using country_ids 5 and 672. Now what happens and why?

    DECLARE

    v_country_name wf_countries.country_name%TYPE;

    v_currency_code wf_countries.currency_code%TYPE;

    e_no_currency EXCEPTION;

    BEGIN

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    BEGIN

    SELECT country_name, currency_code

    INTO v_country_name, v_currency_code

    FROM wf_countries

    WHERE country_id = 5; -- repeat with 672

    IF v_currency_code = 'NONE' THEN

    RAISE e_no_currency;

    END IF;

    END;

    EXCEPTION

    WHEN NO_DATA_FOUND THEN

    DBMS_OUTPUT.PUT_LINE('This country does not exist');

    WHEN e_no_currency THEN

    DBMS_OUTPUT.PUT_LINE('This country exists but has no currency');

    WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('Another type of error occurred');

    END;

    Pentru country_id = 5 :

    Pentru country_id = 672 :

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    Test Quiz: Recognizing the Scope of Exceptions Section 1

    (Answer all questions in this section)

    1. Predefined Oracle Server exceptions such as NO_DATA_FOUND can be raised automatically in inner blocks and handled in outer blocks. True or False? Mark for Review

    (1) Points

    True (*)

    False

    Correct

    2. Non-predefined Oracle Server errors (associated with Oracle error numbers by PRAGMA EXCEPTION_INIT) can be declared and raised in inner blocks and handled in outer blocks. True or False?

    Mark for Review (1) Points

    True

    False (*)

    Correct

    3. What will happen when the following code is executed? DECLARE e_outer_excep EXCEPTION; BEGIN DECLARE e_inner_excep EXCEPTION; BEGIN RAISE e_outer_excep; END; EXCEPTION WHEN e_outer_excep THEN DBMS_OUTPUT.PUT_LINE('Outer raised'); WHEN e_inner_excep THEN DBMS_OUTPUT.PUT_LINE('Inner raised'); END;

    Mark for Review (1) Points

    The code will execute successfully and 'Outer Raised' will be displayed.

    The code will propagate the e_outer_excep back to the calling environment (Application Express).

    The code will fail to compile because e_inner_excep cannot be referenced in the outer block. (*)

    The code will fail to compile because e_inner_excep was declared but never RAISEd.

    Correct

    4. What will happen when the following code is executed?

    DECLARE e_excep1 EXCEPTION; e_excep2 EXCEPTION; BEGIN RAISE e_excep1; EXCEPTION

    WHEN e_excep1 THEN BEGIN

    Mark for Review (1) Points

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    RAISE e_excep2; END; END;

    It will compile successfully and return an unhandled e_excep2 to the calling environment. (*)

    It will fail to compile because you cannot declare more than one exception in the same block.

    It will fail to compile because e_excep1 is out of scope in the subblock.

    It will fail to compile because you cannot have a subblock inside an exception section.

    Correct

    5. There are three employees in department 90. What will be displayed when this code is executed?

    DECLARE v_last_name employees.last_name%TYPE; BEGIN DBMS_OUTPUT.PUT_LINE('Message 1'); BEGIN SELECT last_name INTO v_last_name FROM employees WHERE department_id = 90; DBMS_OUTPUT.PUT_LINE('Message 2'); END; DBMS_OUTPUT.PUT_LINE('Message 3'); EXCEPTION WHEN OTHERS THEN

    DBMS_OUTPUT.PUT_LINE('Message 4'); END;

    Mark for Review (1) Points

    Message 1 Message 3 Message 4

    Message 1 Message 4

    (*)

    Message 1

    An unhandled exception will be propagated back to the calling environment.

    None of the above

    Correct

    6. What will be displayed when the following code is executed?

    DECLARE v_myvar NUMBER; BEGIN v_myvar := 25; DECLARE v_myvar NUMBER := 100; BEGIN outer.v_myvar := 30; v_myvar := v_myvar / 0; outer.v_myvar := 35;

    Mark for Review (1) Points

  • Student: Paun Mihut Catalin

    Master: SIMR

    Anul: II

    Materia: DEZVOLTAREA APLICAIILOR ORACLE

    END; v_myvar := 40; EXCEPTION WHEN ZERO_DIVIDE THEN DBMS_OUTPUT.PUT_LINE(v_myvar); END;

    100

    30 (*)

    35

    25

    40

    Correct