zh的博客

问题：抽奖项目，奖品发放数目多于奖品池数目。操作：减库存之前查询库存，之后update：select quantity from products WHERE id=3;update products set quantity = ($quantity-1) WHERE id=3;在并发情况下，可能会把库存减为负数(两个进程同时select出来的都>0,然后都会执行update)...

项目需求，自定义表头，自由增减字段表结构：查询sql：SELECTCONCAT('{',GROUP_CONCAT(CONCAT('"',l.form_item_code,'"'),':',CONCAT('"',l.value,'"')),'}') dataFROMlottery_charge_form lWHERE l.campaign_id = 217GROUP BY...

只查id：A:id,titleselect * from A where id > (select id from A limit 100000,1) limit 100;select * from A where id between (select id from A limit 100000,1) and(select id from A limit 100100,1);...