android sqlite数据库

创建数据步骤

1、创建一个类 继承 SqliteOpenHelper 实现 onCreate onUpgrade

创建DBHelper

2、创建这个helper类的一个对象，调用getReadableDatabase()方法，会帮我们创建打开一个数据库

DBHelper helper =new DBHelper(mContext);

//调用getReadableDatabase方法，初始化数据库SQLiteDatabase db = helper.getReadableDatabase();

3、增加 删除  修改 查询

DBHelper helper =new DBHelper(mContext);

//调用getReadableDatabase方法，初始化数据库

SQLiteDatabase db = helper.getReadableDatabase();

String name = "张三";

db.execSQL ( "insert into user(name) values(?)",(new Object[]{name}));

db.close();

DBHelper helper =new DBHelper(mContext);

//调用getReadableDatabase方法，初始化数据库

SQLiteDatabase db = helper.getReadableDatabase();

String name = "沈震";

db.execSQL ( "delete from user where id=?",(new Object[]{1}));

db.close();

DBHelper helper =new DBHelper(mContext);

//调用getReadableDatabase方法，初始化数据库

SQLiteDatabase db = helper.getReadableDatabase();

String name = "沈震1";

int id = 1;

db.execSQL ( "update user set name=? where id=?",(new Object[]{name,id}));

db.close();

DBHelper helper =new DBHelper(mContext);

//调用getReadableDatabase方法，初始化数据库

SQLiteDatabase db = helper.getReadableDatabase();

Cursor cursor = db.rawQuery ("select * from user",(new String[]{}));

if (cursor!=null&&cursor.getCount ()>0){

                 while (cursor.moveToNext ()){

                                    String name = cursor.getString (1);

                               Log.i ( "queryDB", "queryDB: "+name );

                  }

     }

  db.close ();