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1、用父节点的left更新，每次更新都会更新与其同级的子节点及 其父节点 及与其父节点同级的节点
if has parent
pleft = parent left
update left = left+2 where left >pleft
update right = right+2 where right>pleft
insert left=pleft +1 ,right = pleft +2
else
insert into left = max(righ ...