The pragma keyword signifies that the statement is a compiler directive, which is not processed when the pl sql is executed. Pl sql provides a feature to handle the exceptions which occur in a pl sql block known as exception handling. Oracle database plsql language reference oracle database plsql language reference oracle database. Oracle has a standard set of exceptions already named as follows. Use the default exceptionhandling model to communicate module status back to calling pl sql programs. You can avoid unhandled exceptions by coding an others handler at the topmost level of every pl sql program. Exception handling oracle plsql best practices book. He is also the bestselling author of oracle8i advanced plsql programming, oracle8 plsql programming, and oracle9i plsql.
Pl sql provides us the exception block which raises the exception thus helping the programmer to find out the fault and resolve it. They are named in the standard package in pl sql and do not need to be defined by the programmer. The exceptions can have different causes such as coding mistakes, bugs, even hardware failures. Plsql allows you to define your own exceptions according to the need of your program. Introduction to pl sql exception handling in oracle database. Plsql exceptions while the plsql parser can analyze the syntax of your plsql program when you compile it, there is no guarantee that the database with which it interacts will even be up and running later when the plsql program executes or that the database objects that are names within your plsql program still exist, let alone reflect the structure that your program requires. The predefined plsql exceptions are declared globally in the package standard and the system raises these exceptions implicitly automatically.
These exceptions are predefined in plsql which get raised when certain database rule is violated. Using exception handling we can test the code and avoid it from exiting abruptly. Apr 19, 2016 few tips for exception handling in plsql use locator variables. Plsql exceptions askhareesh blog on oracle applications. Pl sql exceptions while the pl sql parser can analyze the syntax of your pl sql program when you compile it, there is no guarantee that the database with which it interacts will even be up and running later when the pl sql program executes or that the database objects that are names within your pl sql program still exist, let alone reflect the structure that your program requires. Communicates an application specific error back to a nonplsql host environment.
But without save exceptions we never get past the third element in the bind array. In plsql, an error condition is called an exception. Prior to joining ddr, he was a senior analyst in the languages division of oracle worldwide technical support, focusing on all of oracles language tools. So whenever an exception arises it becomes difficult for us to identify the sql which caused it.
The exception is only raised at the runtime by the plsql engine. Pl sql exceptions plsql tutorial pdf plsql interview. Database programming with plsql dixie state university. Also, if a stored subprogram fails with an unhandled exception, pl sql does not roll back database work done by the subprogram. Exception handling in oracle plsql with example youtube. Following is a list of some important predefined exceptions. Catch all exceptions and convert to meaningful return codes before returning to non pl sql host programs. Exceptions will stop the program from executing further, so to avoid such condition, they need to be captured and handled separately. There are many predefined exception in plsql which are executed when any database rule is violated by the programs. These questions are frequently asked in all it companies. Oracle plsql by example benjamin rosenzweig, elena silvestrova rakhimov. Userdefined exceptions can be defined in the declare section of either the current block or its surrounding block, or in the declare section of a pl sql package.
Plsql provides many predefined exceptions, which are executed when any database rule is violated by a program. You can avoid unhandled exceptions by coding an others handler at the topmost level of every pl sql block and subprogram. The bulk binding feature was introduced in oracle version 8i as the forall statement, which is used for the batch processing of large dml statements without the need of switching between the sql and the pl sql engine for every single row. The video demonstrates examples on how to perform exception handling in oracle pl. Systemdefined exceptions are further divided into two. The following table lists few of the important predefined. Trapping user defined exceptions declarative section.
When an exception is raised, program execution stops and jumps to the nearest exception handler. For example, in the oracle precompilers environment, any database changes made by a failed sql statement or pl sql block are rolled back. Trapping oracle server exceptions functions for trapping exceptions you cannot use sqlcode or sqlerrm directly in an sql statement. Sometimes when we write chunks of code, we write only one exception at the end. Named system exceptions are exceptions that have been given names by pl sql. In pl sql built in exceptions or you make user define exception. By handling the exceptions we can ensure a plsql block does not exit abruptly. It is a pseudoinstruction that tells the compiler to interpret all the occurrences of exception name within the block with the associated oracle server number. Instead, you must assign their values to local variables, then use the variables in the sql statement, as shown in the following example. Oracle pl sql interview question explain ref cursor strongly typed ref cursor and weakly typed ref c duration. We also learn types of exception, predefined and userdefined.
The predefined plsql exceptions are declared globally in the package standard and the system raises these exceptions implicitly. Exceptions in a when clause can be either userdefined or built in. Continue oracle loop past exception catt solutions. When an exception occurs a messages which explains its cause is recieved. Introduction to plsql exception handling in oracle. Exceptions can be internally defined by the runtime system or user defined. Verify preconditions using standardized assertion routines that raise violation exceptions. User defined exceptions in plsql oracle plsql tutorial. Oracle short term course tiet references simplified approach to oracle by kalyani. Raising exceptions in pl sql learn how you can create your own exceptions within plsql and keep your code neat and tidy while you do it.
Save exceptions and forall an exploration oracle live sql. While somewhat limited, it works well and its cheap. Plsql exception error handling interview questions and. Plsql s7l2 trapping oracle server exceptions trapping several predefined oracle server. In this section, you learn three techniques that increase flexibility. Enclosing blocks cannot reference exceptions declared in a subblock because blocks can only reference local or global exceptions predefined exceptions are implicitly raised whenever a pl sql block violates an oracle rule or exceeds a systemdependent limit.
For example, if plsql engine receives an instruction to divide any number by 0, then the plsql engine will throw it as an exception. You define exceptions depending on the requirements of your application. Oracle plsql bulk collect with save exceptions example. I got a list of the indexes from dba team which are non value added to the database with the following conditions quote. Lets start with quizzes to test your knowledge of the basic mechanics of exception handling in plsql. Plsql function with exception handling stack overflow. Pl sql treats all errors that occur in an anonymous block, procedure, or function as exceptions. Predefined exceptions are error conditions that are defined by pl. Mar, 2019 pl sql bulk collect with save exceptions example. Exceptions are designed for run time error handling rather than compile time error handling. There are two types of exceptions defined in pl sql user defined exception. The following is a list of topics that explain how to use exception handling in oracle plsql. Trapping user defined exceptions plsql allows you to define your own exceptions. Predefined exceptions from package standard have predefined names.
Errors that occur during compilation phase are detected by the plsql compiler and reported back to the user. Plsql exception example for beginners and professionals with examples on cursors, triggers, functions, procedures, strings, exceptions, arrays, collections. This is a free video tutorial on oracle pl sql exceptions. Sql wrap the internals of the for loop in its own block and move the exception clause inside the block, now you see the exception is handled and the loop continues, giving us the the value of 3. Examples of built in type internally defined exceptions division by zero, out of memory. My research was with feuersteins oracle pl sql programming, 4th edition, chapter 15 and jonathan gennicks web site hoek wrote. We cannot say that the code is robust until it can handle all the exceptions. The point is that, in those exceptions, shouldnt one allow for the possibility that the cursor may still be open and therefore close it so that there is no memory leak. In this tutorial, we learn oracle plsql exception handling with examples.