一起学Android之Sqlite

 1 package com.hex.demosqlite;
 2 
 3 import android.content.Context;
 4  android.database.sqlite.SQLiteDatabase;
 5  android.database.sqlite.SQLiteOpenHelper;
 6 
 7 /**
 8  * Created by Administrator on 2019/4/4.
 9  */
10 public class DatabaseHelper extends SQLiteOpenHelper {
11 
12     private static final String DB_NAME="persons.db";
13 
14     final int DB_VERSION=115 
16     public DatabaseHelper(Context context) {
17         super(context,DB_NAME,null,DB_VERSION);
18     }
19 
20     21      * 创建数据库，指定数据库名称，版本号
22      * @param db
23      24     @Override
25     void onCreate(SQLiteDatabase db) {
26         String sql="create table person(_id integer primary key autoincrement not null,name char(10),nickname char(10))"27         db.execSQL(sql);
28 29 
30     31      * 数据库升级
32 33  oldVersion
34  newVersion
35      36 37     void onUpgrade(SQLiteDatabase db,1)">int oldVersion,1)">int newVersion) {
38         if(newVersion>oldVersion){
39             onCreate(db);
40         }
41 42 }

 1   2      * 新增
     *
 v
 5       6      add(View v) {
 7         /** //一般不使用此种方法，因为execSQL方法没有返回值
         String sql="insert into person(name,nickname)values('宋江','及时雨')";
 9          db.execSQL(sql);
10          11         ContentValues values = new ContentValues();
12         values.put("name","宋江");
13         values.put("nickname","及时雨"14         //返回值为插入行的行号
15         long result = db.insert("person",values);
16         if (result > 0) {
17             Toast.makeText(this,"插入成功"18         } else {
19             Toast.makeText(20 21     }

 1        * 查询
 query(View v) {
/*
        String sql="select * from person where name=?";
        Cursor cursor = db.rawQuery(sql,new String[]{"宋江"});
10         11         columns 如果为空，则表示所有列
12         Cursor cursor = db.query("person",1)">null,"name=?",1)">new String[]{"宋江"},1)">13         while (cursor.moveToNext()) {
14             int nameIndex = cursor.getColumnIndex("name"15             int nickIndex = cursor.getColumnIndex("nickname"16             String nameValue = cursor.getString(nameIndex);
17             String nickValue = cursor.getString(nickIndex);
18             String s = "name=" + nameValue + ",nickname=" + nickValue;
this        adaper.swapCursor(cursor);
        adaper.notifyDataSetChanged();
23     }

 1          * 更新
 update(View v) {
 String sql="update person set nickname=? where name=?";
 8 
 9         ContentValues values = 10         values.put("nickname","及时雨2"更新语句受影响的行数
12         int result = db.update("person",values,1)">new String[]{"宋江"});
14             Toast.makeText(15         } 16             Toast.makeText(17 18     }

     * 删除
 delete(View v) {
String sql="delete person where name=?";
 9         受删除语句影响的行数
int result = db.delete("person",1)">12             Toast.makeText(13         } 15 16     }