Mybatis-Plus与MySql查询结果出现差异

1、要把以下的一段sql转换成为java语句

SELECT DISTINCT

    c.company_code AS companyCode,

    c.user_name AS userName

FROM user AS c

WHERE CHAR_LENGTH(c.user_name) = 11 AND c.user_name LIKE '1%'

    AND NOT EXISTS (SELECT 1 FROM temp_phone AS p WHERE p.phone = c.user_name)

2、起初我用的查询如下，发现结果与SQL执行结果数据量出现了很大的差异，结果发现likeLeft("user_name", "1")并不能替换c.user_name LIKE '1%'

public List<User> getUserList(List<String> phoneList) {

     return this.list(new QueryWrapper<User>()

    .likeLeft("user_name", "1")

    .eq("CHAR_LENGTH(user_name)", 11)

    .notIn("user_name", phoneList))；

}

3、于是最后修改为

public List<User> getUserList(List<String> phoneList) {

    List<User> userList = this.list(new QueryWrapper<User>()         .eq("CHAR_LENGTH(user_name)", 11)

        .notIn("user_name", phoneList));

    return userList.stream().distinct().filter(user -> user.getUserName().startsWith("1")).collect(Collectors.toList());

}

4、至于为什么likeLeft("user_name", "1")不能替换c.user_name LIKE '1%'，likeLeft到底是个什么情况还在研究中，记录一下，研究好了再来补上