Problem with select Max in the field

For example i got 1 table T1 and has 1 field that names User_ID

User_ID
----
us00019
us00020
us00001
us00002
us00021
us00008
us00005
us00009
us00011
us00010
us00012
us00018

How can i retrive Max User_ID in that field ... i'm using SQL 7.0.. i couldnt do it,anyone got idea. ThankzSELECT MAX(User_ID) FROM T1