android数据库增删改查

ContentValues values = new ContentValues();
values.put("name", "John Doe");
values.put("email", "john.doe@example.com");
long newRowId = db.insert("users", null, values);

String selection = "name = ?";
String[] selectionArgs = { "John Doe" };
int deletedRows = db.delete("users", selection, selectionArgs);

ContentValues values = new ContentValues();
values.put("email", "john.doe.new@example.com");
String selection = "name = ?";
String[] selectionArgs = { "John Doe" };
int updatedRows = db.update("users", values, selection, selection args);

String[] projection = { "name", "email" };
String selection = "name = ?";
String[] selectionArgs = { "John Doe" };
Cursor cursor = db.query("users", projection, selection, selectionArgs, null, null, null);
while (cursor.moveToNext()) {
    String name = cursor.getString(cursor.getColumnIndexOrThrow("name"));
    String email = cursor.getString(cursor.getColumnIndexOrThrow("email"));
}
cursor.close();

try {
    db = openOrCreateDatabase("MyDatabase", MODE_PRIVATE, null);
    // 执行数据库操作
} catch (Exception e) {
    e.printStackTrace();
} finally {
    if (db != null) {
        db.close();
    }
}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    if (oldVersion < 2) {
        db.execSQL("ALTER TABLE users ADD COLUMN age INTEGER");
    }
    if (oldVersion < 3) {
        db.execSQL("CREATE TABLE new_table (id INTEGER PRIMARY KEY, name TEXT)");
        db.execSQL("INSERT INTO new_table (id, name) SELECT id, name FROM users");
    }
}