Order-server/target/classes/mappers/ext/CouponDOMapperExt.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.cdu.lys.graduation.repository.dao.ext.CouponDOMapperExt" >
    <update id="minusCouponNumber">
        UPDATE tb_coupon
        SET `number` = `number` - 1
        WHERE
            id =#{couponId} AND is_delete='n'
    </update>

</mapper>