SQLite的insert、delete、update操作

SQLiteDatabase的学习，我们应该重点掌握execSQL()和rawQuery()方法。 execSQL()方法可以执行insert、delete、update和CREATE TABLE之类有更改行为的SQL语句。

其内部是拼凑SQL语句来实现的，性能没有execSQL()和rawQuery()方法好！！！

public class OtherPersonService {
private DBOpenHelper dbOpenHelper;

public OtherPersonService(Context context) {
this.dbOpenHelper = new DBOpenHelper(context);
}

public void save(Person person){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
ContentValues values = new ContentValues();//通过ContentValues对象来传入参数
values.put("name",person.getName());
db.insert("person",null,values);
}

public void update(Person person){
// update person set name =? where personid =?
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
ContentValues values = new ContentValues();
values.put("name",person.getName());
db.update("person",values,"personid=?",new String[]{person.getId().toString()});
}

public void delete(Integer id){
SQLiteDatabase db = dbOpenHelper.getWritableDatabase();
db.delete("person",new String[]{id.toString()});
}

public Person find(Integer id){
//如果只对数据进行读取，建议使用此方法
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.query("person",new String[]{"personid","name"},
"personid=?",new String[]{id.toString()},null);
//select personid,name from person where personid=? order by ... limit 3,5
if(cursor.moveToFirst()){
int personid = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
return new Person(personid,name);
}
return null;
}

public List<Person> getScrollData(Integer offset,Integer maxResult){
List<Person> persons = new ArrayList<Person>();
SQLiteDatabase db = dbOpenHelper.getReadableDatabase();
Cursor cursor = db.query("person",offset+","+ maxResult);
while(cursor.moveToNext()){
int personid = cursor.getInt(cursor.getColumnIndex("personid"));
String name = cursor.getString(cursor.getColumnIndex("name"));
Person person = new Person(personid,name);
persons.add(person);
}
cursor.close();
return persons;
}

public long getCount() {// select count(*) from person SQLiteDatabase db = dbOpenHelper.getReadableDatabase(); Cursor cursor = db.query("person",new String[]{"count(*)"},null); cursor.moveToFirst(); return cursor.getLong(0); } }

（编辑：李大同）

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