android之SQLite

package com.example.sql;import android.os.Bundle;import android.app.Activity;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import android.database.sqlite.SQLiteOpenHelper;import android.graphics.Color;import android.view.Menu;import android.widget.TextView;public class MainActivity extends Activity {private TextView tv;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);DBHelper db=new DBHelper(this);tv=(TextView)findViewById(R.id.tv);tv.setBackgroundColor(Color.RED);db.clear();//db.insert();//String str=db.query(0);//System.out.println(str);//db.insert();db.insert1(3,"cmaker");String str=db.query(0);tv.setText(str);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}}class DBHelper extends SQLiteOpenHelper{private static final String CREATE_TABLE_SQL="create table TempTb1(_id integer,name text)";private SQLiteDatabase db;DBHelper(Context context){super(context,"test.db",null,2);}@Overridepublic void onCreate(SQLiteDatabase db){db.execSQL(CREATE_TABLE_SQL);}@Overridepublic void onUpgrade(SQLiteDatabase db,int OldVersion,int NewVersion){}public void insert(){String sql="insert into TempTb1(_id,name)values(1,'amaker')";getWritableDatabase().execSQL(sql);}public void insert1(int id,String name){//String sql="insert into TempTb1(_id,name)values(2,'bmaker')";//getWritableDatabase().execSQL(sql);getWritableDatabase().execSQL("insert into TempTb1(_id,name)values(?,?)",new Object[]{id,name});}public String query(int index){SQLiteDatabase db=this.getWritableDatabase();Cursor cur=db.query("TempTb1",null,null,null,null,null,null);if(cur.moveToFirst())//note{cur.move(index);int id=cur.getInt(0);String name=cur.getString(1);String str=id+":"+name;//System.out.println(id+":"+name);db.close();//notereturn str;}return "Fail to find any item";}public void clear(){SQLiteDatabase db=this.getWritableDatabase();db.execSQL("delete from TempTb1");}}