示例
public class MyDbHelper extends SQLiteOpenHelper {
//数据库名字
public static final String DB_NAME = "my.db";
//数据库版本
public static final int DB_VERSION = 1;
public MyDbHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
/**
* 在数据库首次创建的时候调用，创建表以及可以进行一些表数据的初始化
*
* @param db
*/
@Override
public void onCreate(SQLiteDatabase db) {
//创建表
//_id为主键并且自增长一般命名为_id
String sql = "create table person(_id integer primary key autoincrement,name text)";
db.execSQL(sql);
//可以给表初始化一些数据
//db.execSQL("insert into person(name) values('小米')");
}
/**
* 数据库升级的时候回调该方法，在数据库版本号DB_VERSION升级的时候才会调用
*
* @param db
* @param oldVersion
* @param newVersion
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//给表添加一个字段
//db.execSQL("alter table person add age integer");
}
/**
* 数据库打开的时候回调该方法
*
* @param db
*/
@Override
public void onOpen(SQLiteDatabase db) {
super.onOpen(db);
Log.e("xyh", "onOpen: ");
}
}
数据库操作类，封装数据库的增删改查方法
public class DataBaseDao {
private final MyDbHelper mDbHelper;
public DataBaseDao(Context context) {
//实例化数据库管理类
mDbHelper = new MyDbHelper(context);
}
/**
* 插入
*
* @param list
*/
public void insert(List<PersonBean> list) {
SQLiteDatabase db = mDbHelper.getWritableDatabase();
if (db.isOpen()) {
for (int i = 0; i < list.size(); i++) {
db.execSQL("insert into person(name) values(" + "'" + list.get(i).getName() + "'" + ")");
}
db.close();
}
}
/**
* 更新
*
* @param id
* @param personBean
*/
public void update(int id, PersonBean personBean) {
SQLiteDatabase db = mDbHelper.getWritableDatabase();
if (db.isOpen()) {
db.execSQL("update person set name=? where _id=?", new Object[]{personBean.getName(), id});
db.close();
}
}
/**
* 根据id删除
*/
public void delete(int id) {
SQLiteDatabase db = mDbHelper.getWritableDatabase();
if (db.isOpen()) {
db.execSQL("delete from person where _id=?", new Object[]{id});
db.close();
}
}
/**
* 删除所有
*/
public void deleteAll() {
SQLiteDatabase db = mDbHelper.getWritableDatabase();
if (db.isOpen()) {
db.execSQL("delete from person");
//设置id从1开始（sqlite默认id从1开始），若没有这一句，id将会延续删除之前的id
db.execSQL("update sqlite_sequence set seq=0 where name='person'");
db.close();
}
}
/**
* 查询所有
*/
public List<PersonBean> queryAll() {
List<PersonBean> list = new ArrayList<>();
SQLiteDatabase db = mDbHelper.getReadableDatabase();
if (db.isOpen()) {
Cursor cursor = db.rawQuery("select * from person", null);
while (cursor.moveToNext()) {
//int id = cursor.getInt(0);
int _id = cursor.getInt(cursor.getColumnIndex("_id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
PersonBean personBean = new PersonBean(_id, name);
list.add(personBean);
}
cursor.close();
db.close();
}
return list;
}
/**
* 根据id查询
*/
public List<PersonBean> query(int id) {
List<PersonBean> list = new ArrayList<>();
SQLiteDatabase db = mDbHelper.getReadableDatabase();
if (db.isOpen()) {
Cursor cursor = db.rawQuery("select * from person where _id=?", new String[]{id + ""});
while (cursor.moveToNext()) {
//int id = cursor.getInt(0);
int _id = cursor.getInt(cursor.getColumnIndex("_id"));
String name = cursor.getString(cursor.getColumnIndex("name"));
PersonBean dataBean = new PersonBean(_id, name);
list.add(dataBean);
}
cursor.close();
db.close();
}
return list;
}
}
原文链接：https://blog.csdn.net/qq_36699930/article/details/78939698