Example 11-10 Raising an Exception in a Declaration DECLARE -- Raises an error: credit_limit CONSTANT NUMBER(3) := 5000; BEGIN NULL; EXCEPTION WHEN OTHERS THEN -- Cannot catch exception. You declare an exception by introducing its name, followed by the keyword EXCEPTION. Make your programs robust enough to work even if the database is not in the state you expect. For example, perhaps a table you query will have columns added or deleted, or their types changed. this page
WHEN OTHERS THEN -- optional handler for all other errors sequence_of_statements3 END; To catch raised exceptions, you write exception handlers. The inner block does not have an exception handler for C, so exception C propagates to the outer block. Steps to be followed to use unnamed system exceptions are • They are raised implicitly. • If they are not handled in WHEN Others they must be handled explicity. • To Because a block can reference only local or global exceptions, enclosing blocks cannot reference exceptions declared in a sub-block. https://docs.oracle.com/cd/A97630_01/appdev.920/a96624/07_errs.htm
Scope Rules for PL/SQL Exceptions You cannot declare an exception twice in the same block. Named system exceptions are: 1) Not Declared explicitly, 2) Raised implicitly when a predefined Oracle error occurs, 3) caught by referencing the standard name within an exception-handling routine. In such cases, you must use dot notation to specify the predefined exception, as follows: EXCEPTION WHEN invalid_number OR STANDARD.INVALID_NUMBER THEN -- handle the error END; How PL/SQL Exceptions Are Raised
And so on down the line. STORAGE_ERROR 06500 -6500 PL/SQL ran out of memory or memory was corrupted. Place the sub-block inside a loop that repeats the transaction. Functions For Error Trapping Are Contained In Which Section Of A Pl/sql Block When you see an error stack, or sequence of error messages, the one on top is the one that you can trap and handle.
They might point out something in the subprogram that produces an undefined result or might create a performance problem. Oracle Raise Exception With Message For example, when your program selects a column value into a character variable, if the value is longer than the declared length of the variable, PL/SQL aborts the assignment and raises BEGIN ---------- sub-block begins ... LOGIN_DENIED ORA-01017 Invalid name and/or password for the instance.
Skip Headers PL/SQL User's Guide and Reference Release 2 (9.2) Part Number A96624-01 Home Book List Contents Index Master Index Feedback 7 Handling PL/SQL Errors There is nothing more exhilarating than Pl/sql Raises An Exception In Which Two Of The Following Cases Also, it can use the pragma EXCEPTION_INIT to map specific error numbers returned by raise_application_error to exceptions of its own, as the following Pro*C example shows: EXEC SQL EXECUTE /* Execute Topics Raising User-Defined Exception with RAISE Statement Raising Internally Defined Exception with RAISE Statement Reraising Current Exception with RAISE Statement Raising User-Defined Exception with RAISE Statement In Example 11-9, the procedure The error number and message can be trapped like any Oracle error.
RAISE_APPLICATION_ERROR raises an exception but does not handle it. An error message causes the compilation to fail. Pl Sql Exception Handling Examples Consider using a cursor.'); > END; > / Your SELECT statement retrieved multiple rows. Pl Sql Exception Handling Best Practices Oracle Database rolls back to the beginning of the anonymous block.
Command> DECLARE > v_deptno NUMBER := 500; > v_name VARCHAR2 (20) := 'Testing'; > e_invalid_dept EXCEPTION; > BEGIN > UPDATE departments > SET department_name = v_name > WHERE department_id = v_deptno; this website Aliasing problems with parameters PERFORMANCE Condition might cause performance problems. It could represent a mistake, or it could be intentionally hidden by a debug flag, so you might or might not want a warning message for it. NOT_LOGGED_ON ORA-01012 Database connection lost. Pl Sql Continue After Exception
Advantages of PL/SQL Exceptions Using exceptions for error handling has several advantages. Figure7-1, Figure7-2, and Figure7-3 illustrate the basic propagation rules. For example, here is a procedure with unnecessary code that could be removed. http://back2cloud.com/pl-sql/pl-sql-error-exception-handling.php However, the same scope rules apply to variables and exceptions.
Example Since EXCEPTION HANDLING is usually written with the following syntax: EXCEPTION WHEN exception_name1 THEN [statements] WHEN exception_name2 THEN [statements] WHEN exception_name_n THEN [statements] WHEN OTHERS THEN [statements] END [procedure_name]; You Exception Part Can Be Defined Twice In Same Block Make sure you pass negative error numbers to SQLERRM. Some common internal exceptions have predefined names, such as ZERO_DIVIDE and STORAGE_ERROR.
Again, a single exception handler can trap all division-by-zero errors, bad array subscripts, and so on. In the following example, you call raise_application_error if an employee's salary is missing: CREATE PROCEDURE raise_salary (emp_id NUMBER, amount NUMBER) AS curr_sal NUMBER; BEGIN SELECT sal INTO curr_sal FROM emp WHERE Example 11-1 shows several ALTER statements that set the value of PLSQL_WARNINGS. Exception No Data Found Oracle Some common internal exceptions have predefined names, such as ZERO_DIVIDE and STORAGE_ERROR.
INVALID_NUMBER 01722 -1722 n a SQL statement, the conversion of a character string into a number fails because the string does not represent a valid number. (In procedural statements, VALUE_ERROR is Example 11-7 Using RAISE to Raise a Predefined Exception DECLARE acct_type INTEGER := 7; BEGIN IF acct_type NOT IN (1, 2, 3) THEN RAISE INVALID_NUMBER; -- raise predefined exception END IF; Redeclaring predefined exceptions is error prone because your local declaration overrides the global declaration. see here Home Book List Contents Index Master Index Feedback Skip Headers PL/SQL User's Guide and Reference 10g Release 1 (10.1) Part Number B10807-01 Home Book List Contents Index MasterIndex Feedback Previous Next
These conditions are not serious enough to produce an error and keep you from compiling a subprogram. The general syntax to declare unnamed system exception using EXCEPTION_INIT is: DECLARE exception_name EXCEPTION; PRAGMA EXCEPTION_INIT (exception_name, Err_code); BEGIN Execution section EXCEPTION WHEN exception_name THEN handle the exception END; For Example: INVALID_CURSOR 01001 -1001 A program attempts a cursor operation that is not allowed, such as closing an unopened cursor. In Example 11-6, you alert your PL/SQL block to a user-defined exception named out_of_stock.
User-defined error Error defined and raised by the application These must be declared in the declarative section. PL/SQL predefines some common Oracle errors as exceptions. In the following example, you declare an exception named past_due: DECLARE past_due EXCEPTION; Exception and variable declarations are similar. Consider the following example: BEGIN ...
A cursor FOR loop automatically opens the cursor to which it refers.