一、条件函数
if 条件函数 if函数是最常用到的条件函数,其写法是if(xn,a,b), xn代表判断条件,如果xn时,那么结果返回a ,否则返回b。 selectif(age < 25 or age is null, 25岁以下, 25岁以上) as age_cnt,count(1) as number
from table…
Ubuntu Desktop 删除文件 1. right mouse click on the file -> Move to Trash2. right mouse click on the file -> DeleteReferences 1. right mouse click on the file -> Move to Trash
2. right mouse click on the file -> Delete
References …
一、题目
(一) 赛题原文
2024 ICM Problem F: Reducing Illegal Wildlife Trade
Illegal wildlife trade negatively impacts our environment and threatens global biodiversity. It is estimated to involve up to 26.5 billion US dollars per y…
Lecture2: Bellman Equation
State value
考虑grid-world的单步过程: S t → A t R t 1 , S t 1 S_t \xrightarrow[]{A_t} R_{t 1}, S_{t 1} StAt Rt1,St1 t t t, t 1 t 1 t1:时间戳 S t S_t St:时间 t t t时所处的sta…
优化器 MySQL存储引擎中存在了一个可插拔的优化器OPTIMIZER_TRACE,可以看到内部查询计划的TRACE信息,从而可以知道MySQL内部执行过程 查询优化器状态 show variables like optimizer_trace;Variable_name Valueoptimizer_trace enabledoff,one_lineoff…