key-value | 易学教程

Build insert query from array MySQL and PHP

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问题 I'm writing a small web service in PHP and I'm having a bit of trouble getting my head around the following scenario. My plan is to be able to send an array of data to a function, which would then build a query for MySQL to run. In the array I plan for the key to be the column name, and the value to be the value going in to the columns.. i.e. $myData = array('userName'=>'foo','passWord'=>'bar'); $myClass = new users(); $myClass->addUser($myData); Then, in my function I currently have:

Spark: Expansion of RDD(Key, List) to RDD(Key, Value)

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问题 So I have an RDD of something like this RDD[(Int, List)]] Where a single element in the RDD looks like (1, List(1, 2, 3)) My question is how can I expand the key value pair to something like this (1,1) (1,2) (1,3) Thank you 回答1: rdd.flatMap { case (key, values) => values.map((key, _)) } 回答2: And in Python (based on @seanowen's answer): rdd.flatMap(lambda x: map(lambda e: (x[0], e), x[1])) 来源： https://stackoverflow.com/questions/36392938/spark-expansion-of-rddkey-list-to-rddkey-value

Python3之--字典（dict）操作

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1.定义字典的关键字：dict 字典由多个键和其对应的值构成的键—值对组成，每个键值对用冒号 : 分割，每个键值对之间用逗号 , 分割，整个字典包括在花括号 {} 中。 {key1:value1,key2:value2,key3:value3} 在一个字典中：　　key的值是固定不变的，可以是字符串、数字、布尔值、元组。且key的值必须要唯一。　　value的值可以是任意类型。　　字典中的键值对是无序的，不存在索引概念。例如：my_info = {"name":"测试小白", "sex":"male", "city":"杭州", "hobby":"旅游"} 2.字典的查询读取字典当中的数据。根据key来读取值语法：字典变量名[key] 例如： my_info = {"name":"测试小白", "sex":"male", "city":"杭州", "hobby":"旅游"} hobby = my_info["hobby"] print(hobby) 结果：旅游 3.字典的新增如果要为 dict 添加 key-value 对，只需为不存在的 key 赋值即可。语法：字典变量名[新的key] = new_value my_info = {"name":"测试小白", "sex":"male", "city":"杭州", "hobby":"旅游"} my

How do I create a keyValue pair (display field) by combining/having two fields in CakePHP 3?

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问题 I need help getting two values (for human friendly dropdown) in a key-value pair using find or get or anything else. I need help with the simplest method of doing this in CakePHP. Here's my attempt: in my controller $users = $this->LocationsUser->Users->find('list', [ 'limit' => 1, 'keyField' => 'id', 'valueField' => ['first_name', 'last_name'] ])->where(['id' => $id]); In my view echo $this->Form->input('user_id', [ 'options' => $users, 'type' => 'select', 'multiple' => false, ]); The result

How do you create a dictionary in Java? [closed]

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问题 It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center. Closed 7 years ago . I am trying to implement a dictionary (as in the physical book). I have a list of words and their meanings. What data structure / type does Java provide to store a list of words and their meanings as key/value

How do you create a dictionary in Java? [closed]

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How to create dictionary and add key–value pairs dynamically?

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问题 From post: Sending a JSON array to be received as a Dictionary<string,string> I’m trying to do this same thing as that post. The only issue is that I don’t know what the keys and the values are upfront. So I need to be able to dynamically add the key and value pairs and I don’t know how to do that. Does anyone know how to create that object and add key value pairs dynamically? I’ve tried: var vars = [{key:"key", value:"value"}]; vars[0].key = "newkey"; vars[0].value = "newvalue"; But that

How to iterate over associative arrays in Bash

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问题 Based on an associative array in a Bash script, I need to iterate over it to get the key and value. #!/bin/bash declare -A array array[foo]=bar array[bar]=foo I actually don't understand how to get the key while using a for-in loop. 回答1: The keys are accessed using an exclamation point: ${!array[@]} , the values are accessed using ${array[@]} . You can iterate over the key/value pairs like this: for i in "${!array[@]}" do echo "key : $i" echo "value: ${array[$i]}" done Note the use of quotes

MySQL数据库初识

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一数据库概述 1. 数据库？？？　　什么是数据库呢？　　先来看看百度怎么说的数据库，简而言之可视为电子化的文件柜——存储电子文件的处所，用户可以对文件中的数据运行新增、截取、更新、删除等操作。所谓“数据库”系以一定方式储存在一起、能予多个用户共享、具有尽可能小的冗余度、与应用程序彼此独立的数据集合。　　百度的貌似不好理解啊，让我说啊，数据库是存储数据的地方，超哥，你这不是废话么？这位同学，你你你你你说的对，哈哈，存数据的地方是存在哪里呢，存在硬盘上，为什么不是存在内存里面，因为内存无法永久保存。之前我们存数据都是使用的文件，在一个word文档里面写一些羞羞的网址，然后保存，就存储到硬盘上了。有同学就会说了，超哥，我这通过文件不是也将数据保存上了吗？是的，没毛病，但是你想，通过文件来操作数据，效率是不是很低，首先打开关闭就比较慢，其次是我们操作起来也比较麻烦，对不对，如果我想记录一条关于我个人信息的数据，我使用文档来存，是不是很不友好，并且我们要查数据的时候，看图1：图1是一个word里面记录的信息，如果我想查询出所有人的名字，这个操作是不是就很难搞定了，来来来，配合起来~~，你应该说是的，那我就接着说，有同学可能就会说了，老师我用excel啊，看图2，一列就搞定了，没毛病，但是你想打开操作excel效率低不低。并且通过你自己写的程序来操作这些文件是不是很麻烦

JS中key-value存取

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获取Key 在代码中,遇到需要单独提取对象的key值时可使用 Object.keys(object) object是你需要操作的对象 Object.keys()会返回一个存储对象中所有key值的数组获取当前对象每个key对应的值使用 object[key] 参考： https://www.cnblogs.com/zhichong/p/9930309.html ================================================================= JS中key-value存取我们来使用实际的代码测试看看结果 var mArr = ['a','b','c']; var mObj = {}; mObj['key1'] = 1; mObj['key2@'] = 2; //遍历mObj for(var pro in mObj){ if(mObj.hasOwnProperty(pro)){ console.log('key is ' + pro +' and value is' + mObj[pro]); } } console.log(Object.keys(mArr));//结果：(3) ["0", "1", "2"] console.log(Object.keys(mObj));//结果：(2) ["key1", "key2@"]