安卓开发数据库，调用谷歌内部API指令

使用这种方式调用数据库，比常规方式好在，简洁且具有返回值，可以判断是否成功

add：

SQLiteDatabase db=myOpenHelper.getWritableDatabase();
ContentValues values=new ContentValues();
values.put("username", "wangwu");
values.put("password", "110");
long insert=db.insert("user", null, values);
db.close();
if(insert>0){
Toast.makeText(getApplicationContext(), "添加成功", 1).show();
}else{
Toast.makeText(getApplicationContext(), "添加失败", 1).show();
}

delete:

SQLiteDatabase db=myOpenHelper.getWritableDatabase();
int delete=db.delete("user", "username=?", new String[]{"wangwu"});
db.close();
Toast.makeText(getApplicationContext(), "删除了"+delete+"行", 0).show();

 

update:

SQLiteDatabase db=myOpenHelper.getWritableDatabase();
ContentValues values=new ContentValues();
values.put("password", "123456789123");
int update=db.update("user", values, "name=?", new String[]{"wangwu"});
Toast.makeText(getApplicationContext(), "更新了"+update+"行", 0).show();
db.close();

find:

SQLiteDatabase db=myOpenHelper.getWritableDatabase();
//colums代表你要查询的列
Cursor cursor=db.query( "user", new String[]{"password"},"username=?" ,new String[]{"wangwu"}, null, null, null);
if(cursor!=null&&cursor.getCount()>0){
while(cursor.moveToNext()){
String pwd=cursor.getString(0);
System.out.println("password:"+pwd);
}

1.获取数据库

2.对数据库进行操作

此时列：

ContentValues values=new ContentValues();
values.put("password", "123456789123");
int update=db.update("user", values, "name=?", new String[]{"wangwu"});

在这种方法中，sql语句的形式已经写好，缺少一些values

3.操作完毕，关闭数据库