小编fif*_*nik的帖子

-- 2 Moderators: please do not re-format my code

DROP TABLE IF EXISTS `t`;

CREATE TABLE `t` (
      `v` VARCHAR(3) NOT NULL COLLATE 'latin1_general_ci'
    , `c` CHAR(3)    NOT NULL COLLATE 'latin1_general_ci'
    , INDEX `IX_t_v` (`v`)
    , INDEX `IX_t_c` (`c`)
)
;


INSERT INTO t
      (v, c)
VALUES
      ('001', '001')
    , ('002', '002')
    , ('003', '003')
    , ('004', '004')
;

EXPLAIN SELECT c FROM t WHERE c = '001';

EXPLAIN SELECT v FROM t WHERE v = '001';

解释命令给了我：

id  select_type …