SQLite使用小例

package com.peidw.demo;

import java.io.FileNotFoundException;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.util.Log;

/**
 * 数据库操作
 * @author peidw 2009-04-06
 *
 */
public class DatabaseHelper extends SQLiteOpenHelper{
    private Context ctx = null;
    
    public DatabaseHelper(Context context, String name, CursorFactory factory, int version) {
        super(context, name, factory, version);

    }
    

    @Override
    public void onCreate(SQLiteDatabase arg0) {
        
    }
    @Override
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {
        
    }

    

}
package com.peidw.demo;

import java.util.*;
import android.app.*;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.os.*;
import android.util.*;

/**
 * 操作数据库例子
 * @author peidw 2009-04-19
 *
 */
public class ConnectionProvider {
    
    private static  SQLiteDatabase db=null;
    
    
    public  ConnectionProvider(Context ctx) {
        if (db==null){
            Log.v("ConnectionProvider","ctx="+ctx.toString());
            DatabaseHelper dbHelper=new DatabaseHelper(ctx,"StudDB", null,1);
            db= dbHelper.getWritableDatabase();
        }
    }
    
    public SQLiteDatabase getConnection (){
        return db;
    }
    
    public void closeConnection (){
        db.close();
    }
    /**
     * 判断表是否存在
     * @param tablename
     * @return
     */
    public boolean isTableExits(String tablename){
        boolean result=false;//表示不存在
        String str="select count(*) xcount  from sqlite_master where table='"+tablename+"'";
        Cursor c = db.rawQuery(str,null);
        int xcount=c.getColumnIndex("xcount");
        if(xcount!=0){
            result=true; //表存在
        }
        return result;
    }
}

在程序中操作数所的代码片段


 ConnectionProvider cp=new ConnectionProvider(this.getBaseContext());
        // if(cp.isTableExits(TABLE_NAME)){//表已存在
             createTable(cp);
            queryTable(cp);
        // }else{//表不存在
        //     createTable();
        // }



public void createTable( ConnectionProvider cp){
        

        SQLiteDatabase db= cp.getConnection();
        db.execSQL("CREATE TABLE IF NOT EXISTS " + TABLE_NAME + " ("
                + "stud_no" + " TEXT,"
                + "stud_name" + " TEXT"
                + ");");
    
        String sql_1 = "insert into "+ TABLE_NAME +" (stud_no, stud_name) values('S777', 'Lily Chang');";
        String sql_2 = "insert into " + TABLE_NAME +" (stud_no, stud_name) values('S888', 'Linda Lin');";
        String sql_3 = "insert into " + TABLE_NAME +" (stud_no, stud_name) values('S999', 'Bruce Wang');";
        db.execSQL(sql_1); db.execSQL(sql_2); db.execSQL(sql_3);
    }
    public void queryTable(ConnectionProvider cp){
        String str="select * from "+TABLE_NAME;
        Cursor c =cp.getConnection().rawQuery(str,null);
        Log.v("loginactive","查询记录");
        Log.v("loginactive",String.valueOf(c.getCount()) );
        if(c!=null){
            c.moveToFirst();
            while(!c.isLast()){
                Log.v("loginactive","outp.");
                String stud_no=c.getString(0);
                String stud_name=c.getString(1);
                System.out.println(stud_no+"---------------"+stud_name);
                Log.v("loginactive",stud_no+"---------------"+stud_name);
                c.moveToNext();
            }
        }

    }