查询一个数值在数据库里出现的概率。解决方案
查询一个数值在数据库里出现的概率。
我有一个双色球每期开出的号码表，如图：
想问下，如何统计4这个号码，在R1-R6里所有号码里出现的概率（总共有1354条记录，截图只是前5条记录）。
------解决方案--------------------
SELECT sum(sign(FIND_IN_SET('4', concat(r1,',',r2,',',r3,',',r4,',',r5,',',r6))))/count(*)/6 FROM tbl_name
------解决方案--------------------
一直以为双色球不可重号，看了一下规则，原来是可以的
这样就更简单了
select sum(if(r1=4,1,0)+if(r2=4,1,0)+if(r3=4,1,0)+if(r4=4,1,0)+if(r5=4,1,0)+if(r6=4,1,0))/count(*)/6 FROM tbl_name
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1377
52
How to write if in c language to judge multiple conditions
Mar 25, 2024 pm 03:24 PM
In C language, if statement is usually used to execute a specific block of code based on a single condition. However, multiple conditions can be combined to make a determination using logical operators such as &&, ||, and !. Including using logical AND (&&) to judge multiple conditions, using logical OR (||) to judge at least one condition, using logical NOT (!) to judge the negation of a single condition, as well as nesting if statements and using parentheses to clarify priority.
The difference between counta and count
Nov 20, 2023 am 10:01 AM
The Count function is used to count the number of numbers in a specified range. It ignores text, logical values, and null values, but counts empty cells. The Count function only counts the number of cells that contain actual numbers. The CountA function is used to count the number of non-empty cells in a specified range. It not only counts cells containing actual numbers, but also counts the number of non-empty cells containing text, logical values, and formulas.
Asynchronous processing method of Select Channels Go concurrent programming using golang
Sep 28, 2023 pm 05:27 PM
Asynchronous processing method of SelectChannelsGo concurrent programming using golang Introduction: Concurrent programming is an important area in modern software development, which can effectively improve the performance and responsiveness of applications. In the Go language, concurrent programming can be implemented simply and efficiently using Channels and Select statements. This article will introduce how to use golang for asynchronous processing methods of SelectChannelsGo concurrent programming, and provide specific
How to hide the select element in jquery
Aug 15, 2023 pm 01:56 PM
How to hide the select element in jquery: 1. hide() method, introduce the jQuery library into the HTML page, you can use different selectors to hide the select element, the ID selector replaces the selectId with the ID of the select element you actually use; 2. css() method, use the ID selector to select the select element that needs to be hidden, use the css() method to set the display attribute to none, and replace selectId with the ID of the select element.
How to implement change event binding of select elements in jQuery
Feb 23, 2024 pm 01:12 PM
jQuery is a popular JavaScript library that can be used to simplify DOM manipulation, event handling, animation effects, etc. In web development, we often encounter situations where we need to change event binding on select elements. This article will introduce how to use jQuery to bind select element change events, and provide specific code examples. First, we need to create a dropdown menu with options using labels:
How to use if nested statements in MySQL stored procedures
May 26, 2023 pm 12:07 PM
1. Introduction to if statement The if statement is a branching structure statement that performs different operations according to conditions. The if statement usually consists of a conditional expression and one or more statements. If the value of the conditional expression is true, then the statements in the if statement are executed; otherwise, the if statement block is skipped. The syntax of the if statement is as follows: if(condition)thenstatement;elsestatement;endif; where condition is the conditional expression and statement is the SQL statement that needs to be executed. 2. Introduction to if nested statements An if nested statement refers to nesting one or more if statement blocks within an if statement block to perform different operations based on different conditions.
php提交表单通过后,弹出的对话框怎样在当前页弹出,该如何解决
Jun 13, 2016 am 10:23 AM
php提交表单通过后,弹出的对话框怎样在当前页弹出php提交表单通过后,弹出的对话框怎样在当前页弹出而不是在空白页弹出？想实现这样的效果：而不是空白页弹出:------解决方案--------------------如果你的验证用PHP在后端，那么就用Ajax；仅供参考：HTML code
What is the reason why Linux uses select?
May 19, 2023 pm 03:07 PM
Because select allows developers to wait for multiple file buffers at the same time, it can reduce IO waiting time and improve the IO efficiency of the process. The select() function is an IO multiplexing function that allows the program to monitor multiple file descriptors and wait for one or more of the monitored file descriptors to become "ready"; the so-called "ready" state is Refers to: the file descriptor is no longer blocked and can be used for certain types of IO operations, including readable, writable, and exceptions. select is a computer function located in the header file #include. This function is used to monitor file descriptor changes—reading, writing, or exceptions. 1. Introduction to the select function. The select function is an IO multiplexing function.
