A trusted computer system that offers Linux® compatibility and supports contemporary hardware speeds. It is designed to require no porting of common a...
OPatch failed with error code 73（OracleHomeInventory gets null oracleHomeInfo）1、问题描述[oracle@dou_rac2 oraInventory]$/u01/app/oracle/product/11.2.0/dbho...
1.绝对值SQL:select abs(-1) valueO:select abs(-1) value from dual2.取整(大)S:select ceiling(-1.001) valueO:select ceil(-1.001) value from dual3.取整（小）S:select...
解决Ajax跨域问题：Origin xx is not allowed by Access-Control-Allow-Origin.今天一个Ajax跨域问题，纠结我半天，记录之。 title 测试Ajax跨域问题没有结果，chrome用F12 下查看错误 得知：XMLH...
mysql中的where和having子句的区别having的用法having字句可以让我们筛选成组后的各种数据，where字句在聚合前先筛选记录，也就是说作用在group by和having字句前。而 having子句在聚合后对组记录进行筛选。SQL实例：一、显示每个地区的总人口数和总面积．SEL...
改变数据表的结构: alter table tb_name action,[action,action](使用alter table 之前，需要查看数据表的当前定义，需要执行show create table 语句) alter table tb_name modify columns+数...
功能实现：在jsp页面中填写文本框内容，光标离开文本框，在本页面的相应地方获取数据库中改值所对应的其他数据。servlet: 1 request.setCharacterEncoding("utf-8"); 2 PrintWriter out = response.getW...
When I started working on Open Stack, I had to investigate about the HA of the nova component. Unfortunatly the nova configuration needed a single ent...
Galera is a synchronous multi-master cluster for MySQL/InnoDB databases. Some features and benefits of Galera are: Synchronous replication. Multi mast...
Setup MySQL master-master replication with Galera I. Galera introduction MySQL/Galera is synchronous multi-master cluster for MySQL/InnoDB database. T...