estateagents/src/main/resources/mapper/TaLiveActivityMapper.xml

<?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.huiju.estateagents.mapper.TaLiveActivityMapper">

    <update id="addVisitNum" parameterType="java.lang.String">
        UPDATE ta_live_activity t
        SET t.visit_num = IFNULL( t.visit_num, 0 ) + 1
        WHERE
            t.live_activity_id = #{id}
    </update>

</mapper>