其实我们区分in和exists主要是造成了驱动顺序的改变(这是性能变化的关键),如果是exists,那么以外层表为驱动表,先被访问,如果是IN,那么先执行子查询,所以我们会以驱动表的快速返回为目标,那么就会考虑到索引及结果集的关系了 ,另外IN时不对NULL进行处理。 in 是把外表和内表作hash 连接,而exists是对外表作loop循环...
}functionlog(value: Color) {console.log(`Value:${value}`); }for(constvalueofenumKeys(Color)) {log(Color[value]); } https://www.petermorlion.com/iterating-a-typescript-enum/ https://stackoverflow.com/questions/39372804/how-can-i-loop-through-enum-values-for-display-in-radio-buttons err...
enum in Java https://www.geeksforgeeks.org/enum-in-java/ Enumerations serve the purpose of representing a group of named constants in a programming language. For example, the 4 suits in a deck of playing cards may be 4 enumerators named Club, Diamond, Heart, and Spade, belonging to an ...
like in#,we don't sea‘;’toend this statement and we use commas to separate the values*/private enum Seasons{winter,spring,summer,fall}//listthevaluespublic static void main(String[]args){for(Seasonss:Seasons.values()){System.out.println(s);...
The.minand.maxproperties are the minimum and maximum values of anenumtype. When the values of theenumtype are consecutive, they can be iterated over in a for loop within these limits: enumSuit{spades,hearts,diamonds,clubs}for(autosuit=Suit.min;suit<=Suit.max;++suit){writefln("%s: %d",...
for season in Season: print(season) We iterate over enum members in a for loop. for season in Season: print(season.name, season.value) Here we print their names and values. $ python main.py Season.SPRING Season.SUMMER Season.AUTUMN ...
The first value always takes the numeric value of 0, while the other values in the enum are incremented by 1. We also have the option to initialize the first numeric value ourselves. For example, we can write the same enum as: enum PrintMedia { Newspaper = 1, Newsletter, Magazine, ...
In this code snippet, you first define an actions variable, which holds the sequence of methods that you’ll call from DiskPlayer in order to try out the class. Then you create an instance of your disk player class. Finally, you start a for loop to iterate over the list of actions and...
Using a for… in loop Here we will see how to enum gets key by string value in typescript by using for…in loop. Thefor..in loopin typescript is used to loop through the properties of an object. Also, this is used to iterate over the key of an object and do some action on eac...
enum TrafficLight { Green = 0,Yellow = 1, // Duplicate value, OK Red = 1 // Duplicate value, OK } （3）如果enum中的部分成员显式定义了值，⽽部分没有；那么没有定义值的成员还是会按照上⼀个成员的值来递增赋值，例如：enum LoopType { None, // value is 0 Daily, // val...