一起学Android之Sqlite

 1 package com.hex.demosqlite;
 2 
 3 import android.content.Context;
 4 import android.database.sqlite.SQLiteDatabase;
 5 import 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     private static final int DB_VERSION=1;
15 
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     public 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      * @param db
33      * @param oldVersion
34      * @param newVersion
35      */
36     @Override
37     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
38         if(newVersion>oldVersion){
39             onCreate(db);
40         }
41     }
42 }

 1  /**
 2      * 新增
 3      *
 4      * @param v
 5      */
 6     public void add(View v) {
 7         /** //一般不使用此种方法，因为execSQL方法没有返回值
 8          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", null, values);
16         if (result > 0) {
17             Toast.makeText(this, "插入成功", Toast.LENGTH_SHORT).show();
18         } else {
19             Toast.makeText(this, "插入失败", Toast.LENGTH_SHORT).show();
20         }
21     }

 1   /**
 2      * 查询
 3      *
 4      * @param v
 5      */
 6     public void query(View v) {
 7         /*
 8         String sql="select * from person where name=?";
 9         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", null, "name=?", new String[]{"宋江"}, null, null, null);
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;
19             Toast.makeText(this, s, Toast.LENGTH_SHORT).show();
20         }
21         adaper.swapCursor(cursor);
22         adaper.notifyDataSetChanged();
23     }

 1     /**
 2      * 更新
 3      *
 4      * @param v
 5      */
 6     public void update(View v) {
 7         // String sql="update person set nickname=? where name=?";
 8 
 9         ContentValues values = new ContentValues();
10         values.put("nickname", "及时雨2");
11         //更新语句受影响的行数
12         int result = db.update("person", values, "name=?", new String[]{"宋江"});
13         if (result > 0) {
14             Toast.makeText(this, "更新成功", Toast.LENGTH_SHORT).show();
15         } else {
16             Toast.makeText(this, "更新失败", Toast.LENGTH_SHORT).show();
17         }
18     }

 1   /**
 2      * 删除
 3      *
 4      * @param v
 5      */
 6     public void delete(View v) {
 7         //String sql="delete person where name=?";
 8 
 9         //受删除语句影响的行数
10         int result = db.delete("person", "name=?", new String[]{"宋江"});
11         if (result > 0) {
12             Toast.makeText(this, "删除成功", Toast.LENGTH_SHORT).show();
13         } else {
14             Toast.makeText(this, "没有删除成功", Toast.LENGTH_SHORT).show();
15         }
16     }