SSM框架的动态SQL内Set元素错误

Question

<?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">
<mapper namespace="com.experience.dao.User_update_dao">
<update id="modifyUser" parameterType="com.experience.entity.User">
update user 
<set>
<if test="username != null and username != ''">
username = #{username},
</if>
<if test="password != null and password != ''">
password = #{password},
</if>
<if test="sex != null and sex != ''">
sex = #{sex},
</if>
<if test="tel != null and tel != ''">
tel = #{tel},
</if>
<if test="address != null and address != ''">
address = #{address}
</if>
</set>
where id = #{id}
</update>
</mapper>

我也是按照书上敲的，为什么错了呀

Answer 1

请注意看控制台的输出这两句话，

第一处打印了执行的sql语句，第二处提示了语法错误的位置，update user where id = ?，是不是你在测试的时候所有的set都没有进入呢，构建了一个错误的sql语句。