关于sql:SQL-saveOrUpdate

MySQL：ON DUPLICATE KEY UPDATE
参考 https://blog.csdn.net/qq_2277...

PostgreSQL：ON CONFLICT
参考 https://blog.csdn.net/weixin_...

MyBatis：

<selectKey keyProperty="count" resultType="int" order="BEFORE">    select count(1) as count from xxx where aaa=1</selectKey><if test="count > 0">    update set xxx</if><if test="count == 0">    INSERT INTO xxx</if>

Ps：MyBatis的形式在遇到并发插入报反复key时，能够用重试的形式解决