b树的创建从空树开始构建一棵B树每次插入一个关键字不是在树中添加一个叶子结点，因为这样不再是有效的B树而是首先在最低层的某个非终端结点中添加一个关键字，若该结点的关键字个数不超过m-1，则插入完成，否则要产生结点的“分裂”(B tree created from an empty tree began to build a b tree every time insert a keyword is not a leaf node is added in the tree, because it is no longer effective b tree but first of all in one of the lowest layer of the terminal node to add a keyword, if the node number of keywords, no more than m - 1 is inserted into the finish, or to produce node \"split\")