wms-admin/wms-module-system/src/main/resources/mapper/MessageUserMapper.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="top.wms.admin.system.mapper.MessageUserMapper">
    <select id="selectUnreadCountByUserIdAndType" resultType="Long">
        SELECT
            COUNT(t1.message_id)
        FROM sys_message_user AS t1
            LEFT JOIN sys_message AS t2 ON t2.id = t1.message_id
        WHERE t1.user_id = #{userId} AND t1.is_read = false
        <if test="type != null">
            AND t2.type = #{type}
        </if>
    </select>
</mapper>