SQLite基本用法

1.MainActivity.java

import android.app.Activity;

import android.content.ContentValues;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.os.Bundle;

import android.view.Menu;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;



public class MainActivity extends Activity {



    private Button create_database = null;

    private Button update_database = null;

    private Button insert = null;

    private Button update = null;

    private Button query = null;

    private Button delete = null;

    @Override

    public void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        

        create_database = (Button)findViewById(R.id.create_database);

        create_database.setOnClickListener(new CreateDatabaseOnClickListener());

        update_database = (Button)findViewById(R.id.update_database);

        update_database.setOnClickListener(new UpdateDatabaseOnClickListener());

        insert = (Button)findViewById(R.id.insert);

        insert.setOnClickListener(new InsertOnClickListener());

        update = (Button)findViewById(R.id.update);

        update.setOnClickListener(new UpdateOnClickListener());

        query = (Button)findViewById(R.id.query);

        query.setOnClickListener(new QueryOnClickListener());

        delete = (Button)findViewById(R.id.delete);

        delete.setOnClickListener(new DeleteOnClickListener());

    }



    public class CreateDatabaseOnClickListener implements OnClickListener{



        public void onClick(View v) {

            // TODO Auto-generated method stub

            //创建一个DatabaseHelper类的对象，该类是单独一个java文件,这里采用2个参数的构造函数，建立的数据

            //库的名字为tornadomeet.db

            DatabaseHelper database_helper = new DatabaseHelper(MainActivity.this, "tornadomeet.db");

            //只有调用getReadableDatabase()或者getWriteableDatabase()函数后才能返回一个SQLiteDatabase对象

            SQLiteDatabase db = database_helper.getReadableDatabase();

        }                

    }

    

    public class UpdateDatabaseOnClickListener implements OnClickListener{



        public void onClick(View v) {

            // TODO Auto-generated method stub

            DatabaseHelper database_helper = new DatabaseHelper(MainActivity.this, "tornadomeet.db", 2);

            SQLiteDatabase db = database_helper.getReadableDatabase();

        }        

    }

    

    public class InsertOnClickListener implements OnClickListener{



        public void onClick(View v) {

            // 生成contentvallues对象，该对象用来存数据的

            ContentValues values = new ContentValues();

            values.put("id", 1);//注意值的类型要匹配

            values.put("name", "tornado");

            DatabaseHelper database_helper = new DatabaseHelper(MainActivity.this, "tornadomeet.db");

            SQLiteDatabase db = database_helper.getWritableDatabase();//这里是获得可写的数据库

            db.insert("user1", null, values);

        }       

    }

    

    public class UpdateOnClickListener implements OnClickListener{



        public void onClick(View v) {

            // TODO Auto-generated method stub

            DatabaseHelper database_helper = new DatabaseHelper(MainActivity.this, "tornadomeet.db");

            SQLiteDatabase db = database_helper.getWritableDatabase();

            ContentValues values = new ContentValues();

            values.put("name", "tornadomeet");

            //参数1为表名，参数2为更新后的值，参数3表示满足条件的列名称，参数4为该列名下的值

            db.update("user1", values, "id=?", new String[]{"1"});

        }        

    }

    

    public class QueryOnClickListener implements OnClickListener{



        public void onClick(View v) {

            // TODO Auto-generated method stub

            DatabaseHelper database_helper = new DatabaseHelper(MainActivity.this, "tornadomeet.db");

            SQLiteDatabase db = database_helper.getWritableDatabase();

            //查询的语法，参数1为表名；参数2为表中的列名；参数3为要查询的列名；参数时为对应列的值；该函数返回的是一个游标

            Cursor cursor = db.query("user1", new String[]{"id", "name"}, "id=?", new String[]{"1"},  null, null, null);

            //遍历每一个记录

            while(cursor.moveToNext()) {

                String name = cursor.getString(cursor.getColumnIndex("name"));//返回列名为name的值

                System.out.println("query---->" + name);

            }

        }       

    }

    

    public class DeleteOnClickListener implements OnClickListener{



        public void onClick(View v) {

            // TODO Auto-generated method stub

            DatabaseHelper database_helper = new DatabaseHelper(MainActivity.this, "tornadomeet.db");

            SQLiteDatabase db = database_helper.getWritableDatabase();

            //直接删除名为tornadomeet对应的那条记录

            db.delete("user1", "name=?" ,new String[]{"tornadomeet"});

        }

        

    }

    

    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        getMenuInflater().inflate(R.menu.activity_main, menu);

        return true;

    }

}

2.DatabaseHelper.java

import android.content.Context;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteDatabase.CursorFactory;

import android.database.sqlite.SQLiteOpenHelper;



public class DatabaseHelper extends SQLiteOpenHelper {



    private static final int  VERSON = 1;//默认的数据库版本

    

    //继承SQLiteOpenHelper类的类必须有自己的构造函数

    //该构造函数4个参数，直接调用父类的构造函数。其中第一个参数为该类本身；第二个参数为数据库的名字；

    //第3个参数是用来设置游标对象的，这里一般设置为null；参数四是数据库的版本号。

    public DatabaseHelper(Context context, String name, CursorFactory factory, int verson){

        super(context, name, factory, verson);

    }

    

    //该构造函数有3个参数，因为它把上面函数的第3个参数固定为null了

    public DatabaseHelper(Context context, String name, int verson){

        this(context, name, null, verson);

    }

    

    //该构造函数只有2个参数，在上面函数 的基础山将版本号固定了

    public DatabaseHelper(Context context, String name){

        this(context, name, VERSON);

    }

    

    //该函数在数据库第一次被建立时调用

    @Override

    public void onCreate(SQLiteDatabase arg0) {

        // TODO Auto-generated method stub

        System.out.println("create a sqlite database");

        //execSQL()为执行参数里面的SQL语句，因此参数中的语句需要符合SQL语法,这里是创建一个表

        arg0.execSQL("create table user1(id int, name varchar(20))");

    }



    @Override

    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {

        // TODO Auto-generated method stub

        System.out.println("update a sqlite database");

    }



}

3.activity_main.xml

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

 2     xmlns:tools="http://schemas.android.com/tools"

 3     android:layout_width="match_parent"

 4     android:layout_height="match_parent" >

 5 

 6     <Button 

 7         android:id="@+id/create_database"

 8         android:layout_width="fill_parent"

 9         android:layout_height="wrap_content"

10         android:layout_alignParentBottom="true"

11         android:text="@string/create_database"

12         />

13 

14     <Button

15         android:id="@+id/update_database"

16         android:layout_width="fill_parent"

17         android:layout_height="wrap_content"

18         android:layout_above="@id/create_database"

19         android:layout_alignParentLeft="true"

20         android:text="@string/update_database" />

21 

22     <Button

23         android:id="@+id/insert"

24         android:layout_width="fill_parent"

25         android:layout_height="wrap_content"

26         android:layout_above="@id/update_database"

27         android:layout_alignParentLeft="true"

28         android:text="@string/insert" />

29 

30     <Button

31         android:id="@+id/update"

32         android:layout_width="fill_parent"

33         android:layout_height="wrap_content"

34         android:layout_above="@id/insert"

35         android:layout_alignParentLeft="true"

36         android:text="@string/update" />

37     

38     <Button 

39         android:id="@+id/query"

40         android:layout_width="fill_parent"

41         android:layout_height="wrap_content"

42         android:layout_alignParentLeft="true"

43         android:layout_above="@id/update"

44         android:text="@string/query"

45         />

46     <Button 

47         android:id="@+id/delete"

48         android:layout_width="fill_parent"

49         android:layout_height="wrap_content"

50         android:layout_alignParentLeft="true"

51         android:layout_above="@id/query"

52         android:text="@string/delete"

53         />

54         

55 </RelativeLayout>

布局文件