SELECT * FROM `mytable` WHERE CHARACTER_LENGTH(xingming)=2
SELECT CONCAT(LEFT(xingming,1),' ',RIGHT(xingming,1)) FROM `mytable` WHERE CHARACTER_LENGTH(xingming)=2
UPDATE`mytable` SET xingming=CONCAT(LEFT(xingming,1),' ',RIGHT(xingming,1)) WHERE CHARACTER_LENGTH(xingming)=2