Informix如何查看表的主键使用了哪些列?

写的不太好，欢迎高手指点

select c.colno,c.colname,sc.idxname FROM syscolumns c 
join SYSCONSTRAINTS sc on sc.tabid = c.tabid 
join (
    select idxname,part1 as colno from SYSINDEXES si where tabid=107 and part1 >0
    union all 
    select idxname,part2 as colno from SYSINDEXES si where tabid=107 and part2 >0
    union all
    select idxname,part3 as colno from SYSINDEXES si where tabid=107 and part3 >0
    union all
    select idxname,part4 as colno from SYSINDEXES si where tabid=107 and part4 >0
    union all
    select idxname,part5 as colno from SYSINDEXES si where tabid=107 and part5 >0
    union all
    select idxname,part6 as colno from SYSINDEXES si where tabid=107 and part6 >0
    union all
    select idxname,part7 as colno from SYSINDEXES si where tabid=107 and part7 >0
    union all
    select idxname,part8 as colno from SYSINDEXES si where tabid=107 and part8 >0
    union all
    select idxname,part9 as colno from SYSINDEXES si where tabid=107 and part9 >0
    union all
    select idxname,part10 as colno from SYSINDEXES si where tabid=107 and part10 >0
    union all
    select idxname,part11 as colno from SYSINDEXES si where tabid=107 and part11 >0
    union all
    select idxname,part12 as colno from SYSINDEXES si where tabid=107 and part12 >0
) as t on t.colno = c.colno and t.idxname =sc.idxname 
where c.tabid=107 and sc.constrtype = 'P'