Oracle pre-defined several system exceptions and their causes named system exceptions cause access_0000_null undefined object CASE_NOT_FOUND CASE if the corresponding WHEN is not included, when ELSE is not set, the COLLECTION_IS_NULL set element does not initialize the CURSER_ALREADY_OPEN cursor. The DUP_VAL_ON_INDEX unique index column has repeated values INVALID_CURSOR. The INVALID_NUMBER nested SQL statement cannot be operated on the invalid cursor. character conversion to number NO_DATA_FOUND use select into no row is returned, or when TOO_MANY_ROWS executes select into when the index table is not initialized, when the SUBSCRIPT_BEYOND_COUNT element subscript of a result set exceeds the maximum value of a nested table or VARRAY when the SUBSCRIPT_OUTSIDE_LIMIT value of a nested table or VARRAY is used, the variable length is insufficient to accommodate the actual data when the LOGIN_DENIED PL/SQL application connects to the oracle database, an incorrect user name or password NOT_LOGGED_ON PL/SQL application is provided. If the application does not connect to the oralce database, internal problems of data PROGRAM_ERROR PL/SQL may occur. You may need to reinstall the data dictionary & pl. /When the ROWTYPE_MISMATCH host cursor variable in the SQL System package is incompatible with the return type of PL/SQL cursor variable SELF_IS_NULL and the object type is used, when the object method STORAGE_ERROR is called on the null object to run PL/SQL, out of memory space SYS_INVALID_ID invalid ROWID string TIMEOUT_ON_RESOURCE Oracle timeout while waiting for resources