SQLite CRUD操作

SQLite CRUD操作代码实例：

1：首先创建一个继承了SQLiteOpenHelper类的MyDatabaseHelper类。实现他的onCreate(SQLiteDatabase db)

onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)方法。

package dataBase.databasetest;

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

public class MyDatabaseHelper extends SQLiteOpenHelper {
    private Context mContext;

    public MyDatabaseHelper(Context context, String name,
            CursorFactory factory, int version) {
        super(context, name, factory, version);
        mContext=context;
    }

    public static final String CREATE_BOOK="create table book("    //创建book表
            +"id integer primary key autoincrement,"
            +"author text,"
            +"price real,"
            +"pages integer,"
            +"name text)";
     public static final String CREATE_CATEGORY="create table category("  //创建category表
            +"id integer primary key autoincrement,"
            +"category_name text,"
            +"category_code integer)";
    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO 自动生成的方法存根
        db.execSQL(CREATE_BOOK);
        db.execSQL(CREATE_CATEGORY);
        Toast.makeText(mContext, "创建数据库成功", Toast.LENGTH_LONG).show();
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO 自动生成的方法存根
        db.execSQL("drop table if exists book");      //如果已有这两个表。先删除，
        db.execSQL("drop table if exists category");  //在调用onCreate()分别创建
        onCreate(db);
    }

}

2.在MainActivity中通过几个按钮事件测试对数据的CRUD:

 package dataBase.databasetest;

 import android.app.Activity;
 import android.content.ContentValues;
 import android.database.Cursor;
 import android.database.sqlite.SQLiteDatabase;
 import android.os.Bundle;
 import android.util.Log;
 import android.view.View;
 import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.Toast;

 public class MainActivity extends Activity {
     private MyDatabaseHelper dbHelper;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         //修改参数为2，执行onUpgrade()方法跟新数据库
         dbHelper=new MyDatabaseHelper(this, "BookStor.db", null, 2);  //实现构造函数，传入参数，第一个为context。第二个为数据库名称
         //创建表
         Button create=(Button)this.findViewById(R.id.creat);
         create.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 dbHelper.getWritableDatabase();
             }
         });

         //增加数据
         Button add=(Button)this.findViewById(R.id.add);
         add.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 SQLiteDatabase db=dbHelper.getWritableDatabase();
                 ContentValues values=new ContentValues();
                 //开始组装数据
                 values.put("name", "Android第一行代码");
                 values.put("author", "郭霖");
                 values.put("price",66.78);
                 values.put("pages",400 );
                 //写入数据
                 db.insert("book", null, values);
                 values.clear();
                 //准备再次写入数据
                 values.put("name","java讲义");
                 values.put("author", "张三");
                 values.put("price", 66.76);
                 values.put("pages", 789);
                 db.insert("book", null, values);
                 values.clear();
                 Toast.makeText(getApplicationContext(), "数据写入成功", Toast.LENGTH_LONG).show();
             }
         });

         //更新数据
         Button updata=(Button)this.findViewById(R.id.updata);
         updata.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 SQLiteDatabase db=dbHelper.getWritableDatabase();
                 ContentValues values=new ContentValues();
                 values.put("price", 100.00);
                 db.update("book", values, "name=?",new String[]{"平凡的世界"});
                 values.clear();
                 Toast.makeText(getApplicationContext(), "数据更新成功", Toast.LENGTH_SHORT).show();

             }
         });

         //删除数据
         Button delete =(Button)this.findViewById(R.id.delete);
         delete.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 SQLiteDatabase db=dbHelper.getWritableDatabase();
                 db.delete("book", "id>?", new String[]{"23"});     //第一个参数为表名，二三个参数为限制条件
                 Toast.makeText(getApplicationContext(), "数据删除成功", Toast.LENGTH_SHORT).show();
             }
         });

         //查询数据
         Button find =(Button)this.findViewById(R.id.find);
         find.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 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", name);
                         Log.d("MainActivity", author);
                         Log.d("MainActivity", String.valueOf(pages));
                         Log.d("MainActivity", String.valueOf(price));
                     } while (cursor.moveToNext());
                 }
                 cursor.close();
                 Toast.makeText(getApplicationContext(), "数据查找完毕",Toast.LENGTH_SHORT).show();
             }
         });

         //事物
         Button transAction=(Button)this.findViewById(R.id.transaction);
         transAction.setOnClickListener(new OnClickListener() {
             @Override
             public void onClick(View arg0) {
                 SQLiteDatabase db=dbHelper.getWritableDatabase();
                 db.beginTransaction();//开启事务
                 try {
                     ContentValues values=new ContentValues();
                     db.delete("book", "id=?", new String[]{"11"}); //删除
                     values.put("name", "newnewnew");
                     values.put("price",111);
                     values.put("author", "牛人");
                     values.put("pages", 222);
                     db.update("book", values, "name=?", new String[]{"Android第一行代码"});
                     Toast.makeText(getApplicationContext(), "事务执行完毕", Toast.LENGTH_SHORT).show();
                     values.clear();
                 } catch (Exception e) {
                     // TODO: handle exception
                 }finally{
                     db.endTransaction();//关闭事务
                 }
             }
         });
     }
 }

3:查看数据库数据可以通过在dos中运行 adb shell 或者 SQLite Expert软件查看。