错误：无法解析Symbol@styleTheme. Androidstudio in AndroidManifest.html for Kotlin Android Development''

请参阅下面的解决方案，我还提供了在Kotlin中实现CRUD操作的分步过程:

使用SQITE进行CRUD操作

转到AndroidManifest.html

添加这些权限-

<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />

标签下方和标签上方

喜欢这里

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/Theme.Androidstudio"
        tools:targetApi="31">
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

}

class MainActivity : AppCompatActivity() {后

添加此行

private lateinit var db:SQLiteDatabase

setContentView(R.layout.activity_main)后

添加此行

 db = openOrCreateDatabase("employeemanager.db", MODE_PRIVATE,null)

创建表

val createTableQuery = "CREATE TABLE IF NOT EXISTS employee(employeeid INT PRIMARY KEY, name TEXT, phonenumber INT, country TEXT)"
        db?.execSQL(createTableQuery)

插入表格

 val insertQuery = "INSERT INTO employee VALUES("+idtext+",'"+nametext+"',"+phonenumber+",'"+country+"')"
                db?.execSQL(insertQuery)
                Toast.makeText(this@MainActivity, "Inserted Data Successfully!",Toast.LENGTH_SHORT).show()

将提取的数据添加到旋转器

val fetchdata = "SELECT DISTINCT country FROM employee"
        val cursor = db?.rawQuery(fetchdata,null)
        val countries = ArrayList<String>()
        while(cursor!!.moveToNext()) {
            val country1 = cursor.getString(0)
            countries.add(country1)
        }
        cursor?.close()
        var spinner = findViewById<Spinner>(R.id.spinner)
        val spinneradapter = ArrayAdapter<String>(this,android.R.layout.simple_spinner_dropdown_item,countries)
        spinneradapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item)
        spinner.adapter = spinneradapter
        spinner.onItemSelectedListener = object : OnItemSelectedListener {
            override fun onItemSelected(parent: AdapterView<*>, view: View, position: Int, id: Long) {
                selectedItem = parent.getItemAtPosition(position).toString();
                Toast.makeText(this@SecondActivity, "$selectedItem",Toast.LENGTH_SHORT).show()

            }
            override fun onNothingSelected(parent: AdapterView<*>) {
            }
        }

Select 数据并显示

 search.setOnClickListener {
            val searchcountrydata = "SELECT * FROM employee WHERE country =" +"'$selectedItem'";
            val cursor2 = db?.rawQuery(searchcountrydata,null)
            val displayString = StringBuilder()
            while(cursor2!!.moveToNext()) {
                val id = cursor2.getString(0)
                val name = cursor2.getString(1)
                val phonenumber = cursor2.getString(2)
                val country = cursor2.getString(3)
                displayString.append("ID: $id, Name: $name, PhoneNumber: $phonenumber, Country: $country" +"\n")
            }
            display2.text = displayString.toString()
        }

排序数据

sort.setOnClickListener {
            val newquery = "SELECT * FROM employee ORDER BY employeeid DESC"
            val cursor3 = db?.rawQuery(newquery,null)
            val displayString2 = StringBuilder()
            while(cursor3!!.moveToNext()) {
                val id = cursor3.getString(0)
                val name = cursor3.getString(1)
                val phonenumber = cursor3.getString(2)
                val country = cursor3.getString(3)
                displayString2.append("ID: $id, Name: $name, PhoneNumber: $phonenumber, Country: $country" +"\n")
            }
            display2.text = displayString2.toString()
        }

更新数据

updatebutton.setOnClickListener {
            val empval = empid.text.toString()
            val countryval = country.text.toString()
            val updatequery = "UPDATE employee SET country =" + "'$countryval'"+" WHERE employeeid = $empval"
            db?.execSQL(updatequery)
            Toast.makeText(this@ThirdActivity, "Updated Successfully",Toast.LENGTH_SHORT).show()

        }

删除日期

delete.setOnClickListener {
        val rollval = rollno.text.toString();
        val deletequery = "DELETE FROM STUDENT WHERE ROLLNO=$rollval";
        db?.execSQL(deletequery)
        Toast.makeText(this@MainActivity,"Deleted Data Successfully!",Toast.LENGTH_SHORT).show()
    }

在数据中找到最大值和最小值

   maxandmin.setOnClickListener {
 val selectquery1  = "SELECT productid, name, price FROM PRODUCTS p WHERE p.price IN (SELECT MAX(price) FROM PRODUCTS)"
        val selectquery2 = "SELECT productid, name, price FROM PRODUCTS p WHERE p.price IN (SELECT MIN(price) FROM PRODUCTS)"
        val cursor1 = db?.rawQuery(selectquery1, null)
        val cursor2 = db?.rawQuery(selectquery2, null)
        val str = StringBuilder()
        str.append("Maximum Priced Product Details: \n")
        while(cursor1!!.moveToNext()) {
            val id = cursor1.getString(0)
            val name = cursor1.getString(1)
            val price = cursor1.getString(2)
            str.append("Product ID: $id, Product Name: $name, Product Price: $price")
        }
        str.append("\n\nMinimum Priced Product Details: \n")
        while(cursor2!!.moveToNext()) {
            val id = cursor2.getString(0)
            val name = cursor2.getString(1)
            val price = cursor2.getString(2)
            str.append("Product ID: $id, Product Name: $name, Product Price: $price")
        }

查找总计数

str.append("\n\nTotal No Of Products: ")
            val findtotproducts = "SELECT COUNT(*) FROM PRODUCTS"
            val totprice = "SELECT SUM(PRICE) FROM PRODUCTS"
            val cursor4 = db?.rawQuery(findtotproducts,null)
            val cursor5 = db?.rawQuery(totprice, null)

            while(cursor4!!.moveToNext()) {
                val countprod = cursor4.getString(0)
                str.append(countprod)
            }

查找总价

     str.append("\n\nTotal Price of Products: ")
        while(cursor5!!.moveToNext()) {
            val countprod2 = cursor5.getString(0)
            str.append(countprod2)
        }
        display.text = str;