Oracle EXCEPTION
时间: 2023-10-12 21:57:44 浏览: 50
回答: 在Oracle中,EXCEPTION是用于处理异常的关键字。在PL/SQL中,异常可以分为系统预定义异常和用户自定义异常。系统预定义异常是Oracle自动抛出的,例如违反唯一性约束。而用户自定义异常是由编码人员定义的,用于处理非正常情况。[1]
在PL/SQL中,可以使用raise关键字抛出异常,并在异常块中进行处理。另外,还可以使用raise_application_error关键字将异常抛给应用程序,而不在PL/SQL中处理。raise_application_error可以指定错误编号、错误信息和错误布尔值。错误编号的取值范围是-20000到-20999之间。[3]
举个例子,可以使用pragma exception_init语句重写系统预定义异常。比如,可以重写ORA-01476异常(除数为0),并使用raise_application_error抛出自定义异常。[2]
总结起来,Oracle中的EXCEPTION关键字用于处理异常,可以分为系统预定义异常和用户自定义异常。可以使用raise和raise_application_error关键字抛出异常,并在异常块中进行处理或将异常抛给应用程序。
相关问题
oracle exception
Oracle exception refers to the error or exception that occurs during the execution of an Oracle database operation. When an error occurs, Oracle throws an exception, which can be caught and handled by the application.
Oracle provides a set of predefined exceptions that cover common errors, such as invalid data, constraints violations, and system-related issues. These predefined exceptions have names like NO_DATA_FOUND, DUP_VAL_ON_INDEX, and TOO_MANY_ROWS.
In addition to the predefined exceptions, Oracle also allows users to declare and define their custom exceptions using the EXCEPTION keyword. Custom exceptions can be raised explicitly in the PL/SQL code when specific conditions are met.
To handle exceptions in Oracle, you can use the EXCEPTION block in PL/SQL. Inside the block, you can catch specific exceptions using the WHEN clause and perform appropriate actions to handle the error, such as logging the error, displaying a message, or rolling back the transaction.
Here's an example of handling an exception in PL/SQL:
```sql
BEGIN
-- Code that may cause an exception
EXCEPTION
WHEN NO_DATA_FOUND THEN
-- Code to handle the exception
WHEN DUP_VAL_ON_INDEX THEN
-- Code to handle the exception
WHEN OTHERS THEN
-- Code to handle all other exceptions
END;
```
By catching and handling exceptions properly, you can ensure that your application gracefully handles errors and provides meaningful feedback to users.
oracle exception 用法
Oracle异常是指在Oracle数据库中发生的错误或异常情况。在编写PL/SQL代码时,可以使用异常处理机制来捕获和处理这些异常。异常处理机制可以帮助我们更好地控制程序的流程,避免程序崩溃或出现不可预料的错误。在PL/SQL中,可以使用TRY-CATCH语句块来捕获和处理异常。当程序执行到TRY语句块时,如果发生异常,程序会跳转到CATCH语句块中执行异常处理代码。在CATCH语句块中,可以使用RAISE语句来重新抛出异常,或者使用其他方式来处理异常。使用Oracle异常处理机制可以使我们的程序更加健壮和可靠。