电商的库存修改

悲观锁和乐观锁之乐观锁

修改内存的sql

update eb_sku t   set t.stock_inventory = t.stock_inventory - #{quanttity}where t.sku_id = 1020  and t.stock > #{quanttity}

模拟线程并发问题（加上and 可以减少数据并非的问题 判断库存是否足够） 

实例1

update eb_sku t   set t.stock_inventory = t.stock_inventory - 2where t.sku_id = 1020

实例2

update eb_sku t   set t.stock_inventory = t.stock_inventory - 3where t.sku_id = 1020

一些js代码

<c:choose><span style="white-space:pre"></span><c:when test ="${tip == 'stock_error'}"><span style="white-space:pre"></span><p class = "okMsg">对不起货已经被抢光</p><span style="white-space:pre"></span></c:when><span style="white-space:pre"></span><c:otherwise><span style="white-space:pre"></span>---其他内容--<span style="white-space:pre"></span></c:otherwise></c:choose>