Exception raised while validating admin name
Since an Open Read() method could throw one of several exceptions, it is placed in the try block.
If an exception is thrown, it will be caught in the catch block.
And to make to make the user-defined exception look like an Oracle error.
Exceptions are unforeseen errors that happen in your programs.
The code in Listing 15-1 will print message and stack trace information out to the console if an exception is raised.
Note The programs in these lesson cause exceptions on purpose.
In exception handling, more specific exceptions will be caught before their more general parent exceptions.
It is good practice to provide exception handling in your programs.INTO did not return any row.'); END; We can relate the user defined exception to the predefine errcode of oracle using raise_application_error.the advabtage if using this is all previous transactions which are not committed within the PL/SQL Block are rolled back automatically.The exception that you see is generated intentionally to show you what the exception message looks like before you see it yourself in your own programs.Although the code in Listing 15-1 only has a single catch block, all exceptions will be caught there because the type is of the base exception type “Exception”.