Pre-defined Exceptions
| Exception | Oracle Error | SQLCODE | Description |
| ACCESS_INTO_NULL | 06530 | -6530 | It is raised when a null object is autom ... |
| CASE_NOT_FOUND | 06592 | -6592 | It is raised when none of the choices in ... |
| COLLECTION_IS_NULL | 06531 | -6531 | It is raised when a program attempts to ... |
| DUP_VAL_ON_INDEX | 00001 | -1 | It is raised when duplicate values are a ... |
How to handle exceptions in PL/SQL?
An exception is defined as a special condition that changes the program execution flow. The PL/SQL provides you with a flexible and powerful way to handle such exceptions. PL/SQL catches and handles exceptions by using exception handler architecture.
What is user defined exception in Oracle PL/SQL?
User Defined Exceptions in Oracle PL/SQL Oracle also allows custom exception definition. These Exception types are called user defined exceptions. You can create User Defined Exception as follows.
What are the different types of exceptions in SQL Server?
There are two types of exceptions: System exception: the system exception is raised by PL/SQL run-time when it detects an error. For example, NO_DATA_FOUND exception is raised if you select a non-existing record from the database. Programmer-defined exception: the programmer-defined exception is defined by you in a specific application.
What is an exception in Oracle?
An exception is a runtime error or warning condition, which can be predefined or user-defined. Predefined exceptions are raised implicitly (automatically) by the runtime system. User-defined exceptions must be raised explicitly by RAISE statements.
What does exception mean in SQL?
An exception is a PL/SQL error that is raised during program execution, either implicitly by TimesTen or explicitly by your program. Handle an exception by trapping it with a handler or propagating it to the calling environment.
What are the types of exceptions in SQL?
There are three types of exceptions: Predefined exceptions are error conditions that are defined by PL/SQL. Non-predefined exceptions include any standard TimesTen errors. User-defined exceptions are exceptions specific to your application.
Is exception mandatory in PL SQL?
PL/SQL is a block-structured language whose code is organized into blocks. A PL/SQL block consists of three sections: declaration, executable, and exception-handling sections. In a block, the executable section is mandatory while the declaration and exception-handling sections are optional.
Where are exceptions used in PL SQL?
Exceptions can be declared only in the declarative part of a PL/SQL block, subprogram, or package.
Why do we use exception in SQL?
An error occurs during the program execution is called Exception in PL/SQL. PL/SQL facilitates programmers to catch such conditions using exception block in the program and an appropriate action is taken against the error condition. There are two type of exceptions: System-defined Exceptions.
What is trigger in Plsql?
A PL/SQL trigger is a named database object that encapsulates and defines a set of actions that are to be performed in response to an insert, update, or delete operation against a table. Triggers are created using the PL/SQL CREATE TRIGGER statement.
What is package in PL SQL?
A PL/SQL package is a named collection of functions, procedures, variables, cursors, user-defined types, and records that are referenced using a common qualifier, the package name.
Can we use exception in function?
In function, an exception should always either return value or raise the exception further. else Oracle will throw 'Function returned without a value' error at run-time. Transaction control statements can be given at exception handling block.
What are the 3 types of PL SQL statements?
PL/SQL has three categories of control statements: conditional selection statements, loop statements and sequential control statements.
What is named exception?
Named system exceptions are exceptions that have been given names by PL/SQL. They are named in the STANDARD package in PL/SQL and do not need to be defined by the programmer.
What is named block in PL SQL?
2. Named blocks: That's PL/SQL blocks which having header or labels are known as Named blocks. These blocks can either be subprograms like functions, procedures, packages or Triggers.
How do we handle exception in SQL?
To handle exception in Sql Server we have TRY.. CATCH blocks. We put T-SQL statements in TRY block and to handle exception we write code in CATCH block. If there is an error in code within TRY block then the control will automatically jump to the corresponding CATCH blocks.
What is DBMS exception?
An Exception is an error situation, which arises during program execution. When an error occurs exception is raised, normal execution is stopped and control transfers to exceptionhandling part. Exception handlers are routines written to handle the exception.
How do I catch an exception in SQL?
CATCH construct catches all execution errors that have a severity higher than 10 that do not close the database connection. A TRY block must be immediately followed by an associated CATCH block. Including any other statements between the END TRY and BEGIN CATCH statements generates a syntax error.
How do I raise an exception in SQL?
Raising Exceptions DECLARE exception_name EXCEPTION; BEGIN IF condition THEN RAISE exception_name; END IF; EXCEPTION WHEN exception_name THEN statement; END; You can use the above syntax in raising the Oracle standard exception or any user-defined exception.
What is a PL/SQL exception?
PL/SQL treats all errors that occur in an anonymous block, procedure, or function as exceptions. The exceptions can have different causes such as coding mistakes, bugs, even hardware failures.
What are the exceptions in PL/SQL?
PL/SQL has three exception categories: 1 Internally defined exceptions are errors which arise from the Oracle Database environment. The runtime system raises the internally defined exceptions automatically. ORA-27102 (out of memory) is one example of Internally defined exceptions. Note that Internally defined exceptions do not have names, but an error code. 2 Predefined exceptions are errors which occur during the execution of the program. The predefined exceptions are internally defined exceptions that PL/SQL has given names e.g., NO_DATA_FOUND, TOO_MANY_ROWS. 3 User-defined exceptions are custom exception defined by users like you. User-defined exceptions must be raised explicitly.
What is the code that you write to handle exceptions called?
The code that you write to handle exceptions is called an exception handler . A PL/SQL block can have an exception-handling section, which can have one or more exception handler s. Here is the basic syntax of the exception-handling section:
What is a predefined exception in SQL?
Predefined exceptions are errors which occur during the execution of the program. The predefined exceptions are internally defined exceptions that PL/SQL has given names e.g., NO_DATA_FOUND, TOO_MANY_ROWS.
What is internal defined exception?
Internally defined exceptions are errors which arise from the Oracle Database environment. The runtime system raises the internally defined exceptions automatically. ORA-27102 (out of memory) is one example of Internally defined exceptions. Note that Internally defined exceptions do not have names, but an error code.
What happens if exception e1 occurs?
If the exception e1 occurred, the exception_handler1 runs. If the exception e2 occurred, the exception_handler2 executes. In case any other exception raises, then the other_exception_handler runs.
What is Exception
An error occurs during the program execution is called Exception in PL/SQL.
Example of exception handling
Let's take a simple example to demonstrate the concept of exception handling. Here we are using the already created CUSTOMERS table.
Raising Exceptions
In the case of any internal database error, exceptions are raised by the database server automatically. But it can also be raised explicitly by programmer by using command RAISE.
What is a PL/SQL exception?
In PL/SQL, any kind of errors is treated as exceptions. An exception is defined as a special condition that changes the program execution flow. The PL/SQL provides you with a flexible and powerful way to handle such exceptions.
How does PL/SQL handle exceptions?
PL/SQL catches and handles exceptions by using exception handler architecture. Whenever an exception occurs, it is raised. The current PL/SQL block execution halts, control is passed to a separate section called exception section.
What is the exception in Oracle?
Oracle provides many predefined exceptions in the STANDARD package. To define an exception you use EXCEPTION keyword as below: EXCEPTION_NAME EXCEPTION; Code language: SQL (Structured Query Language) (sql)
What is a system exception in SQL?
System exception: the system exception is raised by PL/SQL run-time when it detects an error. For example, NO_DATA_FOUND exception is raised if you select a non-existing record from the database.
What is the exception section?
In the exception section, you can check what kind of exception has been occurred and handle it appropriately. This exception handler architecture enables separating the business logic and exception handling code hence make the program easier to read and maintain.
How many types of exceptions are there in Pl/SQL?
There are two types of Exceptions in Pl/SQL.
What is Exception Handling in PL/SQL?
An exception occurs when the PL/SQL engine encounters an instruction which it cannot execute due to an error that occurs at run-time. These errors will not be captured at the time of compilation and hence these needed to handle only at the run-time.
What happens if it finds the exception handling for the exception which has been raised?
If it found the exception handling for the exception which has been raised, then it will execute that particular handling code part.
How many exceptions can be executed at run time?
Only one exception part can be executed for a block at run-time. After executing it, the controller will skip the remaining exception handling part and will go out of the current block.
Where are exceptions created in Oracle?
They can be created at a subprogram level in the declaration part. These exceptions are visible only in that subprogram. The exception that is defined in the package specification is public exception, and it is visible wherever the package is accessible.
When an exception is raised at runtime, what will the PL/SQL engine look for?
When any exception is raised at runtime, then the PL/SQL engine will look in the exception handling part for that particular exception. It will start from the first ‘WHEN’ clause and, sequentially it will search.
What happens when a PL/SQL engine receives an instruction to divide any number by 0?
For example, if PL/SQL engine receives an instruction to divide any number by ‘0’, then the PL/SQL engine will throw it as an exception. The exception is only raised at the run-time by the PL/SQL engine.
What is exception handlinglets in PL/SQL?
With PL/SQL, a mechanism called exception handlinglets you "bulletproof" your program so that it can continue operating in the presence of errors.
Where can you define exceptions in SQL?
You can define exceptions of your own in the declarative part of any PL/SQL block, subprogram, or package. For example, you might define an exception named insufficient_fundsto flag overdrawn bank accounts. Unlike internal exceptions, user-defined exceptions mustbe given names.
How to handle other Oracle errors?
To handle other Oracle errors, you can use the OTHERShandler. The functions SQLCODEand SQLERRMare especially useful in the OTHERShandler because they return the Oracle error code and message text. Alternatively, you can use the pragma EXCEPTION_INITto associate exception names with Oracle error codes.
Why does the conversion of a character string into a number fail in SQL?
In 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 raised.) This exception is also raised when the LIMIT-clause expression in a bulk FETCHstatement does not evaluate to a positive number.
How do exceptions improve readability?
Exceptions improve readability by letting you isolate error-handling routines. The primary algorithm is not obscured by error recovery algorithms. Exceptions also improve reliability. You need not worry about checking for an error at every point it might occur. Just add an exception handler to your PL/SQL block. If the exception is ever raised in that block (or any sub-block), you can be sure it will be handled.
How to handle raised exceptions?
To handle raised exceptions, you write separate routines called exception handlers. After an exception handler runs, the current block stops executing and the enclosing block resumes with the next statement. If there is no enclosing block, control returns to the host environment.
What happens when an error occurs in SQL?
When an error occurs, an exception is raised. That is, normal execution stops and control transfers to the exception-handling part of your PL/SQL block or subprogram. Internal exceptions are raised implicitly (automatically) by the run-time system. User-defined exceptions must be raised explicitly by RAISEstatements, which can also raise predefined exceptions.
