WARN_Handler and DIE_Handler are the two sub routines i have defined. Whenever db throw errors these routine will get activated. i am calling these methods using SIG { } command See bellow code

$SIG{__WARN__} = \&WARN_Handler;
      $SIG{__DIE__} = \&DIE_Handler;
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here &WARN_Handler and &DIE_Handler are the two sub routines OK. So now tell me how to throw db error as we in JAVA or some languages.