NVL function is used to substitute a value when a null value is encountered.This is useful in PL/SQL programming where we can supply default values when there is a chance of getting null at run time or to provide useful logging messages.
Example is given below.
SQL> set serveroutput on; SQL> -- Created on 12/1/2008 by PLSQLTech Tips SQL> declare -- Local variables here myStr varchar2(100); begin --Initialize the String myStr := 'This is my string'; dbms_output.put_line(nvl(myStr,'This is to replace if string is null')); --Now set the String to null; myStr := null; dbms_output.put_line(nvl(myStr,'This is to replace if string is null')); end; / This is my string This is to replace if string is null PL/SQL procedure successfully completed. SQL>
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