[MyBatis]-10 动态SQL _choose_when_otherwise

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
  "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<!-- 
	namespace: 命名空间, 可以随意定义, 一般情况下要写全限定路径
	MyBatis管理SQL语句是通过namespace+id来定位的
 -->
<mapper namespace="com.lin.mapper.UserMapper">
    
    <select id="selUser1" resultType="User">
        select * from tb_user
        <where>
            <choose>
                <when test="username != null and username !=''">
                    and username = #{username}
                </when>
                <when test="password != null and password !=''">
                    and password = #{password}
                </when>
                <otherwise>
                    and 1 = 1
                </otherwise>
            </choose>
        </where>
    </select>
</mapper>