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sid sname subs
1  jack  |1|2|
2  marry |1|4|
3  tom  |3|
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subid  subname
1      physics
2      maths
3      biology
4      geography
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sid  sname subname
1    jack  physics,maths
2    marry physics,geography
3    tom  biology
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from stuinfo a,subinfo b
where instr(a.subs,'|'||b.subid(+)||'|')>0)
connect by prior rn=rn-1 and prior sid=sid
start with rn=1
group by sid,sname


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