一天一点Android知识（SQLite数据库存储2）

完成SQLite的add,updata,delete,query功能。
MainActivity.java

package com.example.databasetest;

import android.content.ContentValues;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class MainActivity extends AppCompatActivity {

    private MyDatabaseHelper dbHelper;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //dbHelper = new MyDatabaseHelper(this,"BookStore.db",null,1);
        dbHelper = new MyDatabaseHelper(this,"BookStore.db",null,3);
        Button createDatabase =(Button)findViewById(R.id.create_database);
        Button addData = (Button)findViewById(R.id.add_data);
        Button updataData=(Button)findViewById(R.id.updata_data);
        Button deleteButton =(Button)findViewById(R.id.delete_data);
        Button queryButton = (Button)findViewById(R.id.query_data);
        queryButton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                Cursor cursor = db.query("Book",null,null,null,null,null,null);
                if(cursor.moveToFirst()){
                    do{
                        String name = cursor.getString(cursor.getColumnIndex("name"));
                        String author = cursor.getString(cursor.getColumnIndex("author"));
                        int pages = cursor.getInt(cursor.getColumnIndex("pages"));
                        Double price = cursor.getDouble(cursor.getColumnIndex("price"));
                        Log.d("MainActivity","book name is " + name);
                        Log.d("MainActivity","book author is " + author);
                        Log.d("MainActivity","book pages is " + pages);
                        Log.d("MainActivity","book price is " + price);
                    } while (cursor.moveToNext());
                }
                cursor.close();

            }
        });
        deleteButton.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                db.delete("Book","pages>?",new String[]{"500"});
            }
        });
        updataData.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("price",10.99);
                db.update("Book",values,"name=?",new String[]{"The Da Vinci Code"});
            }
        });
        addData.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View view) {
                SQLiteDatabase db = dbHelper.getWritableDatabase();
                ContentValues values = new ContentValues();
                values.put("name","The Da Vinci Code");
                values.put("author","Dan Brown");
                values.put("pages",454);
                values.put("price",16.96);
                db.insert("Book",null,values);
                values.clear();
                values.put("name","The Lost Symbol");
                values.put("author","Dan Brown");
                values.put("pages",510);
                values.put("price",19.95);
                db.insert("Book",null,values);
            }
        });
        createDatabase.setOnClickListener(new View.OnClickListener(){
            public void onClick(View v){
                dbHelper.getWritableDatabase();
            }
        });

    }
}

MyDatabaseHelper.java

package com.example.databasetest;

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

/**
 * Created by Codingbo on 2017/1/19.
 */

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)";

    public static final String CREATE_CATEGORY = "create table Category("+"id integer primary key autoincrement,"+"category_name text,"
    +"category_code integer)";
    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);
        db.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext,"Create succeed",Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("drop table if exists Book");
            db.execSQL("drop table if exists Category");
            onCreate(db);
    }
}

activity_main

"http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    id="@+id/create_database"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Create database"/>

    id="@+id/add_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Add data"/>

    id="@+id/updata_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Updata data"/>

    id="@+id/delete_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Delete data"/>

    id="@+id/query_data"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Query data"/>

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