SQL语句技巧记录（Oracle + MySQL）

Oracle技巧：

1） 获取启动和运行时间
SELECT TO_CHAR (startup_time, 'YYYY-MM-DD HH24:MI:SS') STARTTIME,
TRUNC (SYSDATE - (startup_time)) AS DAYS,
TRUNC ( 24 * ((SYSDATE - startup_time) - TRUNC (SYSDATE - startup_time)) )AS HOURS,
MOD (TRUNC ( 1440 * ( (SYSDATE - startup_time) - TRUNC (SYSDATE - startup_time) ) ), 60) AS MINUTES,
MOD (TRUNC ( 86400 * ( (SYSDATE - startup_time) - TRUNC (SYSDATE - startup_time) ) ), 60) AS SECONDS
FROM v$instance;

2）列出当前连接情况
select * from v$session where username is not null order by logon_time, sid

MySQL对应技巧:
1) 获取启动和运行时间
select SYSDATE() - INTERVAL VARIABLE_VALUE SECOND AS STARTTIME,
(VARIABLE_VALUE div (3600*24)) AS DAYS,(variable_value mod (3600*24) div 3600) AS HOURS,
(variable_value mod (3600) div 60) AS MINUTES, (variable_value mod 60) AS SECONDS
from information_schema.global_status where variable_name like 'UPTIME'

2）列出当前连接情况
select id,user,host,db,command,time,state from information_schema.PROCESSLIST