1，全文索引，相似查询
contains, freetext, contrainstable,freetexttable 等
http://wenku.baidu.com/view/2160f41fff00bed5b9f31dc5.html
http://zhidao.baidu.com/question/249137265.html&__bd_tkn__=7fb94d243b6d8427541be17fe5be29a19a16d5a48078338d51fed8133ea5c69d362ad36bb4bcda3b39bb3949f6bbe47087ac3af56e60b1f4e7eb60157a58f4339e60abfe5b0f03de01252709a334be7d4f03ee7f7e2fcb8dd24c3f7d72594428cf17093148c5a5a2ee0efcaccbdc8d02c23123f14eab