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);        }