注：Mybatis实现批量更新有三种方式，分别是使用foreach标签、使用SQL的case when语句和使用动态SQL的choose语句。具体实现方法如下：
1：使用foreach标签
<update id="batchUpdate" parameterType="java.util.List">
update user set name=#{name}, age=#{age} where id=#{id}
<foreach collection="list" item="item" index="index" separator=";">
update user set name=#{item.name}, age=#{item.age} where id=#{item.id}
</foreach>
</update>2：使用SQL的case when语句
<update id="batchUpdate" parameterType="java.util.List">
update user set name = case id
<foreach collection="list" item="item" index="index" separator=" ">
when #{item.id} then #{item.name}
</foreach>
end,
age = case id
<foreach collection="list" item="item" index="index" separator=" ">
when #{item.id} then #{item.age}
</foreach>
end
where id in
<foreach collection="list" item="item" index="index" open="(" close=")" separator=",">
#{item.id}
</foreach>
</update>3：使用动态SQL的choose语句
<update id="batchUpdate" parameterType="java.util.List">
<foreach collection="list" item="item" index="index" separator=";">
<choose>
<when test="item.name != null and item.age != null">
update user set name=#{item.name}, age=#{item.age} where id=#{item.id}
</when>
<when test="item.name != null">
update user set name=#{item.name} where id=#{item.id}
</when>
<when test="item.age != null">
update user set age=#{item.age} where id=#{item.id}
</when>
</choose>
</foreach>
</update>
