How to randomly query several pieces of data in thinkphp

In developing web applications, it is often necessary to query random data in order to achieve different business logic and effects. In the thinkphp framework, you can use a variety of technologies and methods to implement the function of randomly querying data.

A common method is to use mysql's random function (rand() function). This function can query random data within a certain range by specifying the starting point and end point. For example, to query random data with IDs between 10 and 100 in the $tb_test table, you can use the following code:

<?php use think\Db;

$data = Db::name(&#39;test&#39;)->where('id', 'between', [10, 100])->orderRaw('rand()')->limit(10)->select();

Among them, the where condition specifies the range of IDs, and the orderRaw function specifies the random order. For sorting, the limit function specifies the number of data items to be queried. The disadvantage of this method is low efficiency. When the amount of data in the table is large, the query speed will be significantly slower.

Another method is to use PHP's rand function to implement the function of randomly querying data by writing business logic and functions. The idea is as follows:

First, get the total number of records from the query table, and calculate the ID number of the required record based on the number of records required to be queried.

Then, query the data based on the ID number, and ensure that the queried data is random. Among them, the seed value that controls the randomness of the rand function can be used to ensure the randomness of the query results. In addition, during the code implementation process, be sure to use caching technology to avoid frequent database queries.

The specific code implementation is as follows:

<?php use think\Cache;
use think\Db;

//获取数据表总记录数
$count = Db::name(&#39;test&#39;)->count();

//指定查询记录数
$num = 10;

//生成随机数种子
$seed = rand(0, $count - 1);

//生成id数组
$id_arr = range(1, $count);
shuffle($id_arr);
$id_arr = array_slice($id_arr, 0, $num);

//查询数据
$data = Cache::remember('random_data', function() use ($id_arr) {
    $data = Db::name('test')->where('id', 'in', $id_arr)->select();
    return $data;
}, 60);

Among them, the range function is used to generate an array of a specified range, the shuffle function is used to randomly scramble the array, and the array_slice function is used to intercept the specified length of the array. part. The Cache class is used to implement data caching to avoid frequent database queries. The cache time and cache strategy can be adjusted according to actual business needs.

Both of the above two methods can realize the function of randomly querying data. Which technology to use depends on the actual business scenario and needs. When developing web applications, appropriate technologies and methods should be selected based on performance, efficiency, security and other considerations to optimize functions and improve user experience.

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