操作数据库（增删改查）

package com.example.Caozuo;import android.content.ContentValues;import android.content.Context;import android.database.Cursor;import android.database.sqlite.SQLiteDatabase;import com.example.day_3sqteshu.Chuangjianshujuku;public class Caozuo {    private SQLiteDatabase sq;    public Caozuo(Context context){        Chuangjianshujuku chuangjian = new Chuangjianshujuku(context);        sq = chuangjian.getWritableDatabase();    }    //添加    public boolean add(String name, String arg){        //写数据用的        ContentValues values = new ContentValues();        values.put("name", name);        values.put("aeg", arg);        //存的数据存到数据库        long chuandi = sq.insert("user", null, values);        if (chuandi != -1){            return true;        }else {            return false;        }    }    //修改    public boolean gai(String name, int id){        ContentValues values = new ContentValues();        values.put("name", name);        int chuandi = sq.update("user", values, "id = ?", new String[]{String.valueOf(id)});        if (chuandi >0) {            return true;        }else {            return false;        }    }    //删除    public boolean shanchu(int id){        int chuandi = sq.delete("user", "id = ?", new String[]{String.valueOf(id)});        if (chuandi > 0) {            return true;        }else {            return false;        }    }    //查询+事物    public String chaxunquan(){        try {            //Cursor游标            Cursor cursor = sq.query(false, "user", null, null, null, null, null, null, null);            //封装对象的容器            StringBuffer buffer = new StringBuffer();            while (cursor.moveToNext()) {                //得到数据                String name = cursor.getString(cursor.getColumnIndex("name"));                String arg  = cursor.getString(cursor.getColumnIndex("arg"));                //封装对象                buffer.append("姓名: "+name+" 年龄 : "+arg+"\n");            }            //返回封装对象toString方法            return buffer.toString();        }catch (Exception e) {            e.printStackTrace();        }        return null;    }}