sql 数据库问题 谢谢

UPDATE 表名
SET 字段名 = replace (字段名,'a','zzzzz')
打把字段名里有'a'的替换'zzzzz'了.

UPDATE l_student
set c_code = replace (c_code ,'41','62')

replace不好，很可能其它位置也包含41，可以使用stuff函数
update l_student
set c_code=stuff(c_code,1,2,'62')
where (c_school = '110509') AND (c_year = 2004) and c_code like '41%'

更新之前最好用select查看结果是否有误
select c_code,stuff(c_code,1,2,'62')
from l_student where (c_school = '110509') AND (c_year = 2004) and c_code like '41%'