Android数据库的增删改查

1.首先写一个DB文件

package com.zking.db;

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

/**
 * Created by Administrator on 2017/6/25 0025.
 */

public class DbHelper extends SQLiteOpenHelper{

    /**
     *
     * @param context    上下文
     * @param name        数据库的名字，“文件名.db”
     * @param factory     数据库工厂,null
     * @param version    数据库版本
     */
    public DbHelper(Context context, String name, SQLiteDatabase.CursorFactory factory, int version) {
        super(context, name, factory, version);
        Log.i("test","构造方法");
    }

    //使用该方法：创建表
    //只会调用一次
    @Override
    public void onCreate(SQLiteDatabase db) {
        Log.i("test","创建表");
    }

    //数据库版本  低-->高
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.i("test","升级数据库版本");
    }
}

2.创建数据库和打开连接

  DbHelper dbHelper=new DbHelper(this,"G160628.db",null,2);
        sqLiteDatabase = dbHelper.getWritableDatabase();

  3.直接进行增删改查

public void operation(View view){
        String uname=et_main_uname.getText().toString();
        String upass=et_main_upass.getText().toString();
        //添加 1
        ContentValues contentValues=new ContentValues();
        contentValues.put("uname",uname);
        contentValues.put("upass",upass);
        contentValues.putNull("uid");
        sqLiteDatabase.insert("login","uname",contentValues);
         //添加2
//        for (int i = 0; i <100 ; i++) {
//         sqLiteDatabase.execSQL("insert into login(uname,upass) values('小"+i+"','123')");
//        }

        //修改
        ContentValues contentValues=new ContentValues();
        contentValues.put("uname",uname);
        contentValues.put("upass",upass);
        sqLiteDatabase.update("login",contentValues,"uid=?",new String[]{1+""});

        //删除
        //sqLiteDatabase.delete("login","uid=?",new String[]{102+""});

        //查询
//        sqLiteDatabase.query()
        int pageNo=2;
        int pageSize=3;
        Cursor cursor=sqLiteDatabase.rawQuery("select * from login limit ?,?",new String[]{((pageNo-1)*pageSize)+"",pageSize+""});
        while (cursor.moveToNext()){
            int uid=cursor.getInt(cursor.getColumnIndex("uid"));
            String name=cursor.getString(cursor.getColumnIndex("uname"));
            String pass=cursor.getString(cursor.getColumnIndex("upass"));
            Log.i("test",uid+" "+name+" "+pass);
        }