SQLiteOpenHelper学习

0.视频：http://www.imooc.com/video/3384

1.SQLiteOpenHelper笔记：

2.SQLiteOpenHelper.java代码：

 1 import android.content.Context;
 2 import android.database.sqlite.SQLiteDatabase;
 3 import android.database.sqlite.SQLiteDatabase.CursorFactory;
 4 import android.database.sqlite.SQLiteOpenHelper;
 5 
 6 public class DBOpenHelper extends SQLiteOpenHelper {
 7 
 8     public DBOpenHelper(Context context, String name) {
 9         super(context, name,null, 1);
10         // TODO Auto-generated constructor stub
11     }
12     public DBOpenHelper(Context context, String name, CursorFactory factory,
13             int version) {
14         super(context, name, factory, version);
15         // TODO Auto-generated constructor stub
16     }
17     @Override
18     public void onCreate(SQLiteDatabase db) {
19         // TODO Auto-generated method stub
20        //首次创建数据库时调用 一般有建库建表的操作
21         db.execSQL("create table if not exists stutb(_id integer primary key autoincrement,name text not null,sex text not null,age integer not null)");
22         db.execSQL("insert into stutb(name,sex,age)values('张三','女',18)");
23     }
24 
25     @Override//当数据库的版本发生变化的时候 会自动执行
26     public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
27         // TODO Auto-generated method stub
28 
29     }
30 
31 }
View Code

3.MainActivity.java:

 1 import com.example.sqlitedemo03.DBOpenHelper;
 2 import com.example.sqlitedemo03.MainActivity;
 3 
 4 import android.os.Bundle;
 5 import android.app.Activity;
 6 import android.database.Cursor;
 7 import android.database.sqlite.SQLiteDatabase;
 8 import android.util.Log;
 9 import android.view.Menu;
10 
11 public class MainActivity extends Activity {
12 
13     @Override
14     protected void onCreate(Bundle savedInstanceState) {
15         super.onCreate(savedInstanceState);
16         setContentView(R.layout.activity_main);
17         DBOpenHelper helper =    new DBOpenHelper(MainActivity.this, "stu.db");
18 //        helper.getReadableDatabase();//获取一个只读的数据库 只能查询 不能写入 不能更新
19         SQLiteDatabase db = helper.getWritableDatabase();
20 //        db.query(table, columns, selection, selectionArgs, groupBy, having, orderBy)
21         Cursor c = db.rawQuery("select * from stutb", null);
22         if (c!=null) {
23             String [] cols = c.getColumnNames();
24             while (c.moveToNext()) {
25                 for (String ColumnName : cols) {
26                     Log.i("info", ColumnName+":"+c.getString(c.getColumnIndex(ColumnName)));
27                 }
28             }
29             c.close();
30         }
31         db.close();
32     }
33 }

4.运行结果：

5.小记：构造方法重载的使用。

posted on 2017-02-09 21:45  moonlight.ml  阅读(173)  评论(0)  编辑  收藏  举报

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