Thanks Jurgen.

But if I'm not wrong this command will script the roles : sp_addrole.....

The kind of script I would like to obtain would look like :

if not exists (select * from dbo.sysusers where name = N'xxxxxx' and uid < 16382)

EXEC sp_grantdbaccess N'xxxxxx', N'xxxxxx'

GO

exec sp_addrolemember N'db_datareader', N'xxxxxx'

GO

exec sp_addrolemember N'db_datawriter', N'xxxxxx'

GO

No problem to get the script of sp_grantdbaccess. The trick is to get the "sp_addrolemember".

Regards

Igor