<select id="findUsersByUserName2" resultType="java.util.Map" parameterType="Params">
2 SELECT
3 id as uid,
4 username as uname,
5 password as pwd,
6 account as act,
7 telephone,
8 idcard,
9 create_time as createTime,
10 is_delete as isDelete,
11 male,
12 birthday,
13 email,
14 address,
15 update_time as updateTime,
16 teacher_id as teacherId,
17 subject_id as subjectId,
18 age,
19 status,
20 type
21 FROM
22 tz_user
23 WHERE
24 username LIKE '%${username}%'
25 AND `password` = #{password}
26 ORDER BY ${order}
27 </select>
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ORDER BY ${order} 和模糊查询 username LIKE '%${username}%' 是用$符号，其他的大多是用 #{} 来获取传递的参数。
ORDER BY 还可以用#{}符号传递参数。
#{} 将传入的数据都当成一个字符串，会对自动传入的数据加一个双引号。如：order by #{userId}，如果传入的值是111, 那么解析成sql时的值为order by "111", 如果传入的值是id，则解析成的sql为order by "id".
${} 将传入的数据直接显示生成在sql中，是什么就是什么，没有加双引号：select * from table1 where id=${id} 若 id = 4，则就是：select * from table1 where id = 4;
最好是能用 #{} 就用它，因为它可以防止sql注入，且是预编译的，在需要原样输出时才使用 ${}
记住一点：单引号里面的用 ${} 符号，ORDER BY 可以用${}或者#{}符号，用 #{} 的不能加单引号，因为默认加了引号