sqlite的应用

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent">  
    <Button  
        android:id="@+id/insert"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="插入"/>  
    <Button  
        android:id="@+id/updataG"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="更新分数"/>  
    <Button  
        android:id="@+id/updataA"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="更新年龄"/>  
    <Button  
        android:id="@+id/delete"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="删除"/>  
   <Button  
        android:id="@+id/select"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="查找"/>  
    <Button  
        android:id="@+id/display"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="显示当前数据库"/>  
    <Button  
        android:id="@+id/close"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"  
        android:text="关闭"/>  
    <ListView   
        android:id="@+id/listview"  
        android:layout_width="fill_parent"  
        android:layout_height="wrap_content"></ListView>  
</LinearLayout>  

import java.lang.String;  
public class Student {  
    int _id;//与所建立的表对应  
    String name;  
    int age;  
    int grade;  
    String info;  
    public Student(String name,int age,int grade,String info){  
        this.name=name;  
        this.age=age;  
        this.grade=grade;  
        this.info=info;  
    }  
    public Student(){  
          
    }  
} 

import java.util.ArrayList;  
import java.util.List;  
import android.os.Bundle;  
import android.util.Log;  
import android.widget.ArrayAdapter;  
import android.widget.Button;  
import android.widget.ListView;  
import android.widget.Toast;  
import android.app.Activity;  
import android.content.ContentValues;  
import android.database.Cursor;  
import android.database.sqlite.SQLiteDatabase;  
import android.view.View;  
import android.view.View.OnClickListener;  
public class MainActivity extends Activity implements OnClickListener{  
    public static final String DB_NAME="studentdata.db";  
    Button insertBtn;  
    Button updataGBtn;  
    Button updataABtn;  
    Button deleteBtn;  
    Button selectBtn;  
    Button displayBtn;  
    Button closeBtn;  
    ListView mListView;  
    SQLiteDatabase db;  
    @Override  
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.activity_main);  
        mListView=new ListView(this);  
        BtnInit();  
        OpenCreateDB();  
    }  
    public void OpenCreateDB(){  
        db = openOrCreateDatabase(DB_NAME, this.MODE_PRIVATE, null);  
        db.execSQL("DROP TABLE IF EXISTS students");    
        db.execSQL("CREATE TABLE IF NOT EXISTS students (_id INTEGER PRIMARY KEY AUTOINCREMENT, name VARCHAR, age INTEGER,grade INTEGER, info VARCHAR)");  
    }  
    //插入数据到students表  
    public void InsertData(){  
        Student liSi =new Student("李四", 22, 87, "南京邮电大学 通信工程");  
        Student liHua = new Student("李华", 23, 78, "南京邮电大学 软件工程");  
        db.execSQL("INSERT INTO students VALUES (NULL,?,?,?,?)", new Object[]{"张三",21,98,"南京邮电大学 电子信息工程"});  
        db.execSQL("INSERT INTO students VALUES (NULL,?,?,?,?)", new Object[]{liSi.name,liSi.age,liSi.grade,liSi.info});  
        db.execSQL("INSERT INTO students VALUES (NULL,‘王五‘,19,99,‘南京邮电大学 网络工程‘)");  
        ContentValues cvOfLiHua = new ContentValues();  
        cvOfLiHua.put("name", liHua.name);  
        cvOfLiHua.put("age", liHua.age);  
        cvOfLiHua.put("grade", liHua.grade);  
        cvOfLiHua.put("info", liHua.info);  
        db.insert("students", null, cvOfLiHua);  
        Log.d("msg","插入结束");  
        Toast.makeText(this, "插入数据完成！", Toast.LENGTH_SHORT).show();  
    }  
    public void UpdateGrade(){  
        ContentValues cv = new ContentValues();    
        cv.put("grade", 85);    
        //更新数据,将李四的成绩改为85分  
        db.update("students", cv, "name = ?", new String[]{"李四"});    
        Log.d("msg","李四的成绩已更新");  
        Toast.makeText(this, "李四的成绩已更新", Toast.LENGTH_SHORT).show();  
    }  
    public void UpdateAge(){  
        String sqlString="UPDATE students SET age=18 WHERE grade= 78";  
        db.execSQL(sqlString);  
        Log.d("msg","李华的年龄已更新");  
        Toast.makeText(this, "李华的年龄已更新", Toast.LENGTH_SHORT).show();  
    }  
    public void Delete(){  
        db.execSQL("DELETE FROM students WHERE name=‘张三‘");  
        Log.d("msg","张三的信息已经被删除");  
        Toast.makeText(this, "张三的信息已经被删除", Toast.LENGTH_SHORT).show();  
    }  
    public void Select(){  
        List<String> list=new ArrayList<String>();  
        Cursor c = db.rawQuery("SELECT * FROM students WHERE grade >= ?", new String[]{"86"});  
        Log.d("msg","--------------大于86分的同学----------------------------");  
        while (c.moveToNext()) {  
            Student person = new Student();  
            person._id = c.getInt(c.getColumnIndex("_id"));  
            person.name = c.getString(c.getColumnIndex("name"));  
            person.grade=c.getInt(c.getColumnIndex("grade"));  
            person.age = c.getInt(c.getColumnIndex("age"));  
            person.info = c.getString(c.getColumnIndex("info"));  
            String string=""+person._id+" "+person.name+" "+person.grade+" "+person.age+" "+person.info;  
            list.add(string);  
            Log.d("msg",string);  
        }  
        c.close();  
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1,list);  
        mListView.setAdapter(adapter);  
    }  
    public void Display(){  
        List<String> list=new ArrayList<String>();  
        Cursor c = db.rawQuery("SELECT * FROM students", null);  
        while (c.moveToNext()) {  
            Student person = new Student();  
            person._id = c.getInt(c.getColumnIndex("_id"));  
            person.name = c.getString(c.getColumnIndex("name"));  
            person.grade=c.getInt(c.getColumnIndex("grade"));  
            person.age = c.getInt(c.getColumnIndex("age"));  
            person.info = c.getString(c.getColumnIndex("info"));  
            String string=""+person._id+" "+person.name+" "+person.grade+" "+person.age+" "+person.info;  
            list.add(string);  
            Log.d("msg",string);  
        }  
        c.close();  
        ArrayAdapter<String> adapter=new ArrayAdapter<String>(this, android.R.layout.simple_expandable_list_item_1,list);  
        mListView.setAdapter(adapter);  
    }  
    public void Close(){  
        db.close();  
    }  
    public void BtnInit(){  
        insertBtn=(Button)findViewById(R.id.insert);  
        updataGBtn=(Button)findViewById(R.id.updataG);  
        updataABtn=(Button)findViewById(R.id.updataA);  
        deleteBtn=(Button)findViewById(R.id.delete);  
        selectBtn=(Button)findViewById(R.id.select);  
        displayBtn=(Button)findViewById(R.id.display);  
        closeBtn=(Button)findViewById(R.id.close);  
        mListView=(ListView)findViewById(R.id.listview);  
        insertBtn.setOnClickListener(this);  
        updataABtn.setOnClickListener(this);  
        updataGBtn.setOnClickListener(this);  
        deleteBtn.setOnClickListener(this);  
        selectBtn.setOnClickListener(this);  
        displayBtn.setOnClickListener(this);  
        closeBtn.setOnClickListener(this);  
    }  
    @Override  
    public void onClick(View v) {  
        // TODO Auto-generated method stub  
        switch(v.getId()){  
        case R.id.insert:  
            InsertData();  
            break;  
        case R.id.updataA:  
            UpdateAge();  
            break;  
        case R.id.updataG:  
            UpdateGrade();  
            break;  
        case R.id.display:  
            Display();  
            break;  
        case R.id.delete:  
            Delete();  
            break;  
        case R.id.select:  
            Select();  
            break;  
        case R.id.close:  
            Close();  
            break;  
        }  
    }  
}