i had a feeling that perl would be able to accomplish this. i.e. for level of 3, generate this output 
SELECT t1.name AS lev1,t2.name AS lev2,t3.name AS lev3
FROM tab AS t1
LEFT JOIN tab AS t2 ON t2.parentID = t1.ID
LEFT JOIN tab AS t3 ON t3.parentID = t2.ID
WHERE t1.parentID = 0

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the purpose is to retrieve the whole tree from adjacent-list table with depth as an parameter.

In reply to generate self join sql with specified depth level by Anonymous Monk

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