摘要：
Create TABLE tab (CurNum VARCHAR(10),PreNum VARCHAR(10))INSERT INTO tabSELECT '1', Null UNION ALL SELECT '2', '1' UNION ALL SELECT '3', '2' UNION ALL SELECT '4', '1' UNION ALL SELECT '5', Nullselect * from tabSELECT CurNum,PreNum,path=C 阅读全文