Sybase SQL Anywhere 12 - Get all indexes which are unique -> ambigious sysindexes error
There are two system views called sysindexes - one owned by SYS and one owned by DBO. You likely want the the one owned by SYS:

SELECT z.name FROM sys.sysobjects z JOIN sys.sysindexes ON (z.id = i.id) WHERE type = 'U'