join

转换方法 var people = ["p1", "p2", "p3", 1, 2, 3, true, false]; console.log(people); console.log(typeof people); console.log(people instanceof Array); console.log(Array.isArray(people)); console.log(people.toString()); console.log(typeof people.toString()); console.log(people.toLocaleString()); console.log(typeof people.toLocaleString()); console.log(people.join()); // 默认用逗号, 分开各个元素 console.log(people.join(',')); console.log(people.join(' ')); console.log(people.join('-')); 来源： https://www.cnblogs.com/buildnewhomeland/p/12411441.html

关于left join...on...and...以及left join...on...where的区别，网上很多的说法是对于left join...on...and...，and所限定的条件只对关联字段起作用，比如select a.* from tmp_table_a a left join tmp_table_b b on a.col1=b.col1 and b.col2=xx,很多人认为条件b.col2=xx是不起作用的。 对于这种说法，我个人是不认同的，至少来讲，这是一种不负责任的说法。以下是我的一些测试例子，从这里大家就可以理解这两个用法的区别。 select count(*) from tb_bo_valusr_new where month=201010 and brand=3;--141858 select count(*) from tb_bo_valusr_new where month=201010;---2281189 select count(distinct usr_nbr) from tb_bo_valusr_new where brand=3;--152110 select count(distinct usr_nbr) from tb_bo_valusr_new where month=201010;--2281189 select count(*

//当前线程等待thread线程完成后才从join()返回 package com.mao; import java.util.concurrent.TimeUnit; public class Join { public static void main(String[] args) throws Exception { Thread previous = Thread.currentThread(); for(int i=0;i<10;i++) { Thread thread = new Thread(new Domino(previous),String.valueOf(i)); thread.start(); previous = thread; } System.out.println("juinr"); TimeUnit.SECONDS.sleep(4); System.out.println(Thread.currentThread().getName()+" terminate."); } } class Domino implements Runnable{ private Thread thread; public Domino(Thread thread) { this.thread=thread; } [@Override](https://my

7.2.2. The WHERE Clause 7.2.2.where子句 The syntax of the WHERE Clause is where子句的语法如下： WHERE search_condition where search_condition is any value expression (see Section 4.2) that returns a value of type boolean . search_condition可以是任何返回Boolean类型的值表达式（参见 4.2节 ）。 After the processing of the FROM clause is done, each row of the derived virtual table is checked against the search condition. If the result of the condition is true, the row is kept in the output table, otherwise (i.e., if the result is false or null) it is discarded. The search condition typically references at least one column of

第一种方法：in string = 'helloworld' if 'world' in string: 　　print 'Exist' else: 　　print 'Not exist' 第二种方法：find string = 'helloworld' if string.find(’world‘) == 5: #5的意思是world字符从那个序开始，因为w位于第六个，及序为5，所以判断5 　　print 'Exist' else: 　　print 'Not exist' 第三种方法：index，此方法与find作用类似，也是找到字符起始的序号 if string.index(’world‘) > -1: #因为-1的意思代表没有找到字符，所以判断>-1就代表能找到 　　print 'Exist' 如果没找到，程序会抛出异常 ---------------------------------------------------------------------------------------------------------------------------------- 1：strip()方法，去除字符串开头或者结尾的空格 >>> a = " a b c " >>> a.strip() 'a b c' 2：lstrip()方法，去除字符串开头的空格 >>> a = "