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在android开发中,sqlite

SQLite是一种轻量级的关系型数据库管理系统,它被广泛用于移动设备和嵌入式系统中。在Android开发中,SQLite被用于存储和检索应用程序的数据。以下是如何在Android中使用SQLite的步骤: 1. 创建SQLite数据库:在AndroidManifest.xml文件中,添加SQLite数据库的权限。在您的Activity中,创建一个SQLiteOpenHelper对象,它将帮助您管理数据库的创建和升级。 ```java public class DatabaseHelper extends SQLiteOpenHelper { private static final String DATABASE_NAME = "MyDatabase.db"; private static final int DATABASE_VERSION = 1; public DatabaseHelper(Context context) { super(context, DATABASE_NAME, null, DATABASE_VERSION); } @Override public void onCreate(SQLiteDatabase db) { String CREATE_TABLE = "CREATE TABLE Student (" + "id INTEGER PRIMARY KEY AUTOINCREMENT, " + "name TEXT NOT NULL, " + "age INTEGER NOT NULL);"; db.execSQL(CREATE_TABLE); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS Student"); onCreate(db); } } ``` 2. 插入数据:使用SQLiteOpenHelper对象的getWritableDatabase()方法获取到一个可以写入的SQLite数据库连接,然后使用SQL语句插入数据。 ```java public void insertData() { SQLiteDatabase db = dbHelper.getWritableDatabase(); ContentValues contentValues = new ContentValues(); contentValues.put("name", "John"); contentValues.put("age", 20); long result = db.insert("Student", null, contentValues); if (result == -1) { Log.e("Database", "Failed to insert data"); } else { Log.e("Database", "Inserted data"); } db.close(); } ``` 3. 查询数据:使用SQLiteOpenHelper对象的getReadableDatabase()方法获取到一个可以读取的SQLite数据库连接,然后使用SQL语句查询数据。 ```java public List<Student> fetchData() { List<Student> studentList = new ArrayList<>(); SQLiteDatabase db = dbHelper.getReadableDatabase(); Cursor cursor = db.rawQuery("SELECT * FROM Student", null); while (cursor.moveToNext()) { Student student = new Student(); student.setId(cursor.getInt(cursor.getColumnIndex("id"))); student.setName(cursor.getString(cursor.getColumnIndex("name"))); student.setAge(cursor.getInt(cursor.getColumnIndex("age"))); studentList.add(student); } cursor.close(); db.close(); return studentList; } ``` 4. 更新数据:使用SQLiteOpenHelper对象的getWritableDatabase()方法获取到一个可以写入的SQLite数据库连接,然后使用SQL语句更新数据。 ```java public void updateData() { SQLiteDatabase db = dbHelper.getWritableDatabase(); ContentValues contentValues = new ContentValues(); contentValues.put("name", "John Doe"); contentValues.put("age", 21); int result = db.update("Student", contentValues, "id = ?", new String[]{String.valueOf(1)}); if (result == 0) { Log.e("Database", "Failed to update data"); } else { Log.e("Database", "Updated data"); } db.close(); } ``` 5. 删除数据:使用SQLiteOpenHelper对象的getWritableDatabase()方法获取到一个可以写入的SQLite数据库连接,然后使用SQL语句删除数据。 ```java public void deleteData() { SQLiteDatabase db = dbHelper.getWritableDatabase(); int result = db.delete("Student", "id = ?", new String[]{String.valueOf(1)}); if (result == 0) { Log.e("Database", "Failed to delete data"); } else { Log.e("Database", "Deleted data"); } db.close(); } ``` 以上就是在Android中使用SQLite的基本步骤。 [2023-11-07 22:44:06 | AI问答 | 794点数解答]

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