数据库查询结果随机排序
1.查询结果随机排序
Oracle查询结果集，随机排序
select * from table1 order by dbms_random.value();
MySQL随机查询出一条记录
-- 下面的查询语句效率高，不要使用 SELECT * FROM table1 ORDER BY rand() LIMIT 1 来查询 SELECT * FROM table1 WHERE id=(SELECT id FROM table1 ORDER BY rand() LIMIT 1)
查询结果集，随机排序
SELECT * FROM table1 ORDER BY rand()
MS SQL Server
SELECT * FROM table ORDER BY NEWID()
SELECT TOP 10 * FROM table ORDER BY NEWID()
2.查看当前数据库所有触发器信息
SELECT object_name(a.parent_obj) as [表名] ,https://www.wendangku.net/doc/5b4618510.html, as [触发器名称] ,(case when b.is_disabled=0 then '启用' else '禁用' end) as [状态] ,b.create_date as [创建日期] ,b.modify_date as [修改日期] ,c.text as [触发器语句] FROM sysobjects a INNER JOIN sys.triggers b ON b.object_id=a.id INNER JOIN syscomments c ON c.id=a.id WHERE a.xtype='tr' ORDER BY [表名]
SELECT TOP 10
[session_id],
[request_id],
[start_time] AS '开始时间',
[status] AS '状态',
[command] AS '命令',
dest.[text] AS 'sql语句',
DB_NAME([database_id]) AS '数据库名',
[blocking_session_id] AS '正在阻塞其他会话的会话ID',
der.[wait_type] AS '等待资源类型',
[wait_time] AS '等待时间',
[wait_resource] AS '等待的资源',
[dows].[waiting_tasks_count] AS '当前正在进行等待的任务数',
[reads] AS '物理读次数',
[writes] AS '写次数',
[logical_reads] AS '逻辑读次数',
[row_count] AS '返回结果行数'
FROM sys.[dm_exec_requests] AS der
INNER JOIN [sys].[dm_os_wait_stats] AS dows
ON der.[wait_type]=[dows].[wait_type]
CROSS APPLY
sys.[dm_exec_sql_text](der.[sql_handle]) AS dest
WHERE [session_id]>50
ORDER BY [cpu_time] DESC
3.快速删除整个数据库中的所有表
select 'truncate table ' + Name + ';' from sysobjects where xtype='U' order by name asc;
4.金额大小写转换
function AmountLtoU(num) {
///
///金额
if(isNaN(num))return "无效数值！";
var strPrefix="";
if(num<0)strPrefix ="(负)";
num=Math.abs(num);
if(num>=1000000000000)return "无效数值！";
var strOutput = "";
var strUnit = '仟佰拾亿仟佰拾万仟佰拾元角分';
var strCapDgt='零壹贰叁肆伍陆柒捌玖';
num += "00";
var intPos = num.indexOf('.');
if (intPos >= 0){
num = num.substring(0, intPos) + num.substr(intPos + 1, 2);
}
strUnit = strUnit.substr(strUnit.length - num.length);
for (var i=0; i < num.length; i++){
strOutput += strCapDgt.substr(num.substr(i,1),1) + strUnit.substr(i,1);
}
return strPrefix+strOutput.replace(/零角零分
$/, '整').replace(/零[仟佰拾]/g, '零').replace(/零{2,}/g, '零').replace(/零([亿|万])/g, '$1').replace(/零+元/, '元').replace(/亿零{0,3}万/, '亿').replace(/^元/, "零元");
};
3.中文乱码。设置URL的时候:
jdbc:mysql://localhost:3306/database?useUnicode=true&characterEncoding=UTF-8
Tomcat的会话超时可以在多个级别上设置：tomcat实例级别、Web应用级别、servlet级别以及运行时Context代码级别。 较低级别的设定会覆盖较高级别的设定。
Tomcat可以在以下几个地方设置session超时：
1 Web容器级别
在conf/web.xml中
Xml代码
1.
2.
3.
4.
5.
6.
7.
这里是以分钟为单位的，默认是30分；
2 webapp级别
在webapp中的 WEB-INF/web.xml
Xml代码
1.
2.
3.
4.
3 应用程序代码中：硬编码
Java代码
1.session.setMaxInactiveInterval（30*60）;//以秒为单位
session.setMaxInactiveInterval（30*60）;//以秒为单位
优先级，越细粒度优先级越高，也就是3>2>1
4 还要一种配置，但现在比较少见了，因为需要将Context配置在server.xml里：
这就是修改conf/server.xml
Xml代码
1.
3. isWARValidated="false" isInvokerEnabled="true"
4. isWorkDirPersistent="false"/>
isWARValidated="false" isInvokerEnabled="true"
isWorkDirPersistent="false"/> 单位为秒