Hello! every people

I need values increase sequentially for fill the field, for example:

i have the table (5 record):

field1 field2 field3
null Jhon 23
null peter 22
null carl 19
null Katherine 15
null sthefany 20

I need the same table but information next:

field1 field2 field3
1 Jhon 23
2 peter 22
3 carl 19
4 Katherine 15
5 sthefany 20

This change i need in store proceduce. The system is firbird 1.5

Thank You, yours help