问题描述
假设您有一个包含 user,url,datetime 的表格，其中每一行代表一次网站访问。
如何查找既访问过包含字符串模式 A 的 URL 又访问包含字符串模式 B 的 URL 的用户？
事实上它“包含一个字符串模式......”，而不是一个简单的相等性使得不可能使用类似的查询
url in ('action1.PHP','action2.PHP')
就像在SQL querying a customer ID who ordered both product A and B中一样。
解决方法
您可以使用 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<form>
<h4>Q1:</h4>
<label>answer1</label>
<input type="radio" name="q1" value="answer1" data-id="1" class="answer">
<label>answer2</label>
<input type="radio" name="q1" value="answer2" data-id="2" class="answer">
<label>answer3</label>
<input type="radio" name="q1" value="answer3" data-id="3" class="answer">
<h4>Q2:</h4>
<label>answer1</label>
<input type="radio" name="q2" value="answer1" data-id="4" class="answer">
<label>answer2</label>
<input type="radio" name="q2" value="answer2" data-id="5" class="answer">
<label>answer3</label>
<input type="radio" name="q2" value="answer3" data-id="6" class="answer" checked>
<div>
<input type="submit" value="Submit">
</div>
</form> 和 group by：
having如果不想重复比较，可以省略 select user
from t
where url like '%a%' or
url like '%b%'
group by user
having sum(url like '%a%') > 0 and
sum(url like '%b%') > 0;
子句或使用：
where假设“/testing”和“/staging”是两种 URL 模式。你可以用这个
package com.example.newsapp
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.newsapp.databinding.ActivityMainBinding
import kotlinx.coroutines.*
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import java.lang.Exception
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private lateinit var adapter: RecyclerAdapter
private val newsTitles = mutableListOf<String>()
private val newsImages = mutableListOf<String>()
private val newsAuthors = mutableListOf<String>()
private val newsDescriptions = mutableListOf<String>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
makeAPIRequest()
}
private fun initRecyclerView() {
adapter = RecyclerAdapter( newsTitles,newsImages,newsAuthors,newsDescriptions)
binding.rvNews.layoutManager = LinearLayoutManager(this)
binding.rvNews.adapter = adapter
}
private fun addToList(title:String,image:String,author:String,description:String){
newsTitles.add(title)
newsImages.add(image)
newsAuthors.add(author)
newsDescriptions.add(description)
}
private fun makeAPIRequest() {
val api = Retrofit.Builder()
.baseUrl("https://newsapi.org/")
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(APIService::class.java)
GlobalScope.launch(Dispatchers.IO){
val response = api.getNews()
val posts = response.body()
try{
if (posts != null) {
for(art in posts.Articles){
Log.i("Main Activity","Result = $art")
addToList(art.Title,art.urlToImage,art.Author,art.Description)
}
}
withContext(Dispatchers.Main){
initRecyclerView()
}
} catch (e:Exception){
Log.e("Main Activity",e.toString())
}
}
}
}
如果您需要有关模式匹配的更多信息，可以搜索“模式匹配 SQL”和“SQL 正则表达式”。