Here is my sample code
path = 'D:\\temp'
connection = "test1.sde"
arcpy.CreateDatabaseConnection_management(path,
connection,
"ORACLE",
instanse,
"DATABASE_AUTH",
"test",
XXX,
"SAVE_USERNAME",
"",
database,
"TRANSACTIONAL",
<version_name>,"")
tablePath = path + "\\" + connection
arcpy.env.workspace = tablePath
with arcpy.da.UpdateCursor(arcpy.env.workspace,[<field_name>], where) as cur:
# updatecursor stuff come here