mysql的in会不会让索引失效?
mysql的in会让索引失效吗？不会！看结果：
mysql>descselect*fromtb_provincewherenamein('lily3','lily2','lily1');
+----+-------------+-------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
|id|select_type|table|partitions|type|possible_keys|key|key_len|ref|rows|filtered|Extra|
+----+-------------+-------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
|1|SIMPLE|tb_province|NULL|ALL|NULL|NULL|NULL|NULL|108780|30.00|Usingwhere|
+----+-------------+-------------+------------+------+---------------+------+---------+------+--------+----------+-------------+
1rowinset,1warning(0.00sec)
mysql>altertabletb_provinceaddindexg(name);
QueryOK,0rowsaffected(0.29sec)
Records:0Duplicates:0Warnings:0
mysql>descselect*fromtb_provincewherenamein('lily3','lily2','lily1');
+----+-------------+-------------+------------+-------+---------------+------+---------+------+------+----------+-----------------------+
|id|select_type|table|partitions|type|possible_keys|key|key_len|ref|rows|filtered|Extra|
+----+-------------+-------------+------------+-------+---------------+------+---------+------+------+----------+-----------------------+
|1|SIMPLE|tb_province|NULL|range|g|g|34|NULL|3|100.00|Usingindexcondition|
+----+-------------+-------------+------------+-------+---------------+------+---------+------+------+----------+-----------------------+
1rowinset,1warning(0.00sec)
mysql>
顺便说下，in查出的结果，不一定按in排序，如下：
mysql>select*fromtb_provincewherenamein('lily3','lily2','lily1');
+----+-------+-------+------+------+------+------+------+------+------+------+------+------+------+
|id|name|score|x|x1|x2|x3|x4|x5|x6|x7|x8|x9|x10|
+----+-------+-------+------+------+------+------+------+------+------+------+------+------+------+
|1|lily1|1|0|0|0|0|0|0|0|0|0|0|0|
|2|lily2|2|0|0|0|0|0|0|0|0|0|0|0|
|3|lily3|3|0|0|0|0|0|0|0|0|0|0|0|
+----+-------+-------+------+------+------+------+------+------+------+------+------+------+------+
3rowsinset(0.00sec)
mysql>
总结
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