It is raised when a cursor fetches value in a variable having incompatible data type. It is raised when PL/SQL has an internal problem.
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It is raised when a database call is issued without being connected to the database. It is raised when a SELECT INTO statement returns no rows. It is raised when a program attempts to log on to the database with an invalid username or password. It is raised when the conversion of a character string into a number fails because the string does not represent a valid number. It is raised when attempts are made to make a cursor operation that is not allowed, such as closing an unopened cursor. It is raised when duplicate values are attempted to be stored in a column with unique index.
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It is raised when a program attempts to apply collection methods other than EXISTS to an uninitialized nested table or varray, or the program attempts to assign values to the elements of an uninitialized nested table or varray. It is raised when none of the choices in the WHEN clause of a CASE statement is selected, and there is no ELSE clause. It is raised when a null object is automatically assigned a value. The following table lists few of the important pre-defined exceptions − Exception For example, the predefined exception NO_DATA_FOUND is raised when a SELECT INTO statement returns no rows. PL/SQL provides many pre-defined exceptions, which are executed when any database rule is violated by a program. This program asks for a customer ID, when the user enters an invalid ID, the exception invalid_id is raised.ĭbms_output.put_line('ID must be greater than zero!') Įnter value for cc_id: -6 (let's enter a value -6) The following example illustrates the concept. The syntax for declaring an exception is − A user-defined exception must be declared and then raised explicitly, using either a RAISE statement or the procedure DBMS_STANDARD.RAISE_APPLICATION_ERROR. PL/SQL allows you to define your own exceptions according to the need of your program. You can raise the Oracle standard exceptions in a similar way. In the next section, we will give you an example on raising a user-defined exception. You can use the above syntax in raising the Oracle standard exception or any user-defined exception. Following is the simple syntax for raising an exception − Raising ExceptionsĮxceptions are raised by the database server automatically whenever there is any internal database error, but exceptions can be raised explicitly by the programmer by using the command RAISE. Since there is no customer with ID value 8 in our database, the program raises the run-time exception NO_DATA_FOUND, which is captured in the EXCEPTION block. The above program displays the name and address of a customer whose ID is given.
#Define invalid code
When the above code is executed at the SQL prompt, it produces the following result − We will be using the CUSTOMERS table we had created and used in the previous chapters −ĭBMS_OUTPUT.PUT_LINE ('Name: '|| c_name) ĭBMS_OUTPUT.PUT_LINE ('Address: ' || c_addr) ĭbms_output.put_line('No such customer!') Let us write a code to illustrate the concept.
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The default exception will be handled using WHEN others THEN − Here you can list down as many exceptions as you can handle. The general syntax for exception handling is as follows. PL/SQL supports programmers to catch such conditions using EXCEPTION block in the program and an appropriate action is taken against the error condition. An exception is an error condition during a program execution. In this chapter, we will discuss Exceptions in PL/SQL.