SQL sentence to insert where updated rows is zero...

Hi guys,

It's just to ask you if there is a single SQL sentence to INSERT
values in case of UPDATE WHERE returns 0 rows updated. I mean, If I
write something like,

# update my_table set column1='value' where column2='key_value';

And system replies me with one "UPDATE 0" because there is no row at
column2 with value 'key_value'... is it possible to say here: in this
case, create one new row with 'value' - 'key_value'...?  like

# insert into my_table (column1, column2) values ('value', 'key_value');

Glus