Update mejdu 2 tablici v MS SQL

Hi,
Imam sledniq problem, iskam da napravq update mejdu 2 tablici v MS SQL 2000.
Ednata tablica(testbase) sudurja IP-ta s prazen username a drugata(StudentInfo) sudurja vsi4ki usernames sus suotvetnite IP-a(ne6to kato katalog). Iskam da napravq taka 4e update-a da slaga username sre6tu vsiako IP v purvata tablica(testbase).

Probvah slednata spravka:

Update testbase
SET testbase.ClientUserName = StudentInfo.username
FROM
studentinfo
WHERE
testbase.clientip = studentinfo.dialinip

no mi dava slednata gre6ka:

Server: Msg 8152, Level 16, State 2, Line 1
String or binary data would be truncated.
The statement has been terminated.

Imate li predstava kade gre6a ili druga ideq za ispulnenie na update-a?
Blagodarq predvaritelno:)

eba ti error message-a! naprawo me ubi. Po ideia query-to e

Update testbase
SET testbase.ClientUserName = StudentInfo.username
FROM
studentinfo , testbase
WHERE
testbase.clientip = studentinfo.dialinip

oba4e toia error gowori za drug problem (oswen deto ti lipswa testbase vav from klauzata)

Na men tova sab6tenie mi govori, 4e

testbase.ClientUserName e s po-malka LENGTH ot StudentInfo.username