


The database has a column store that stores the names of malls. Now I want the mall to be Taobao, with Amazon ranked first. The other malls are sorted by data creation time, and paging is required.
There is a solution
MySQL provides a method of sorting by field, but filed must include all mall types that already exist in the database, otherwise the ones not included will disrupt the sorting, but the malls under the store (such as Nichia, etc.) will be successively added increase, so this sql statement will continue to change. So I wanted to ask if there are any good solutions.
2 Add a field corresponding to the digital ID of the store, and sort by the digital ID. However, the product now wants Taobao and Amazon to be ranked first, but Chao Lingxi wants Nichia to be ranked first. Wouldn’t this logic be disrupted?
Please tell me if you have any good plans.
Reply content:
The database has a column store that stores the names of malls. Now I want the mall to be Taobao, with Amazon ranked first. The other malls are sorted by data creation time, and paging is required.
There is a solution
MySQL provides a method of sorting by field, but filed must include all mall types that already exist in the database, otherwise the ones not included will disrupt the sorting, but the malls under the store (such as Nichia, etc.) will be added one after another. Increase, so this sql statement will continue to change. So I wanted to ask if there are any good solutions.
Second, add a field corresponding to the digital ID of the store, and sort by the digital ID. However, the product now wants Taobao and Amazon to be ranked first, but Chaolingxi wants Nichia to be ranked first. Wouldn’t this logic be disrupted?
Please tell me if you have any good plans.
This question requires two fields: one is weight and the other is sort.
You look like this
Taobao: weight: 100 sort: 1,
Amazon: weith: 100 sort: 2,
日亚: weight: 100 sort: 3
Others: weight: 1 sort: 1
...
Your sql is written like this: select * from table order by weight * sort
, this solves the problem. If you want to change permissions, you can adjust weight or sort
Complex logical sorting should not be done at the database level, but should be placed at the code level, such as in a sortable array or map. Just define the sorting rules yourself. JDK has many sorted arrays and maps

php把负数转为正整数的方法:1、使用abs()函数将负数转为正数,使用intval()函数对正数取整,转为正整数,语法“intval(abs($number))”;2、利用“~”位运算符将负数取反加一,语法“~$number + 1”。

实现方法:1、使用“sleep(延迟秒数)”语句,可延迟执行函数若干秒;2、使用“time_nanosleep(延迟秒数,延迟纳秒数)”语句,可延迟执行函数若干秒和纳秒;3、使用“time_sleep_until(time()+7)”语句。

php字符串有下标。在PHP中,下标不仅可以应用于数组和对象,还可应用于字符串,利用字符串的下标和中括号“[]”可以访问指定索引位置的字符,并对该字符进行读写,语法“字符串名[下标值]”;字符串的下标值(索引值)只能是整数类型,起始值为0。

php除以100保留两位小数的方法:1、利用“/”运算符进行除法运算,语法“数值 / 100”;2、使用“number_format(除法结果, 2)”或“sprintf("%.2f",除法结果)”语句进行四舍五入的处理值,并保留两位小数。

判断方法:1、使用“strtotime("年-月-日")”语句将给定的年月日转换为时间戳格式;2、用“date("z",时间戳)+1”语句计算指定时间戳是一年的第几天。date()返回的天数是从0开始计算的,因此真实天数需要在此基础上加1。

在php中,可以使用substr()函数来读取字符串后几个字符,只需要将该函数的第二个参数设置为负值,第三个参数省略即可;语法为“substr(字符串,-n)”,表示读取从字符串结尾处向前数第n个字符开始,直到字符串结尾的全部字符。

方法:1、用“str_replace(" ","其他字符",$str)”语句,可将nbsp符替换为其他字符;2、用“preg_replace("/(\s|\ \;||\xc2\xa0)/","其他字符",$str)”语句。

查找方法:1、用strpos(),语法“strpos("字符串值","查找子串")+1”;2、用stripos(),语法“strpos("字符串值","查找子串")+1”。因为字符串是从0开始计数的,因此两个函数获取的位置需要进行加1处理。


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