Use a random number generator - here is one way. Perhaps there are ways to shorten this, but it should work:UPDATE YourTable SET
FirstName =
CHAR(65+ABS(CHECKSUM(NewId())) % 25) +
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25),
LastName =
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)+
CHAR(65+ABS(CHECKSUM(NewId())) % 25)