android studio 数据库表的创建

1、首先创建一个MyDatabaseHelper文件用来处理sql语句

package com.example.myapplication;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.widget.Toast;

public class MyDatabaseHelper extends SQLiteOpenHelper {

    public static final String CREATE_BOOK="Create table Book("
            +"id integer primary key autoincrement,"
            +"author text,"
            +"price real,"
            +"pages integer,"
            +"name text)";
    private Context mContext;
    public MyDatabaseHelper(Context context,String name,SQLiteDatabase.CursorFactory factory, int version){
        super(context,name,factory,version);
        mContext=context;
    }
    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(CREATE_BOOK);
        Toast.makeText(mContext,"Create succeed", Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}

2、写MainActivity3主代码

package com.example.myapplication;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;

import androidx.appcompat.app.AppCompatActivity;

public class MainActivity3 extends AppCompatActivity {
    private MyDatabaseHelper dbHelper;
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main3);
        dbHelper=new MyDatabaseHelper(this,"BookStore.db",null,1);
        Button createDatabase=(Button) findViewById(R.id.create_database);
        createDatabase.setOnClickListener(new View.OnClickListener(){

            @Override
            public void onClick(View view) {
                dbHelper.getWritableDatabase();
            }
        });
    }
}

3、写布局文件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context=".MainActivity3">

    <Button
        android:id="@+id/create_database"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Create database"
        app:layout_constraintVertical_bias="0"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>


</androidx.constraintlayout.widget.ConstraintLayout>

4、在AndroidManifest.xml文件中定义了一个Activity（活动），声明一个名为MainActivity3的Activity

        <activity
            android:name=".MainActivity3"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity> 

5、结果展示：

6、ctrl shift A，搜索Device explorer

7、使用DB Browser导入表