android studio的sqlite的增删改查代码

我可以为您提供基本的Android Studio中SQLite数据库的增删改查代码示例。首先，您需要在您的项目中创建一个SQLiteOpenHelper类，以便在您的应用程序中打开、创建、升级和维护SQLite数据库。

以下是一个例子：

public class DatabaseHelper extends SQLiteOpenHelper {

    private static final String DATABASE_NAME = "mydatabase.db";
    private static final int DATABASE_VERSION = 1;

    // Table name and column names
    private static final String TABLE_NAME = "mytable";
    private static final String COLUMN_ID = "id";
    private static final String COLUMN_NAME = "name";
    private static final String COLUMN_AGE = "age";

    // SQL statement to create the table
    private static final String SQL_CREATE_TABLE =
            "CREATE TABLE " + TABLE_NAME + " (" +
                    COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    COLUMN_NAME + " TEXT, " +
                    COLUMN_AGE + " INTEGER)";

    public DatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // create the table
        db.execSQL(SQL_CREATE_TABLE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // Upgrade the database if needed
    }

    // Insert data into the table
    public long insertData(String name, int age) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, name);
        values.put(COLUMN_AGE, age);
        long result = db.insert(TABLE_NAME, null, values);
        db.close();
        return result;
    }

    // Retrieve data from the table
    public Cursor getData() {
        SQLiteDatabase db = this.getReadableDatabase();
        String[] projection = {COLUMN_ID, COLUMN_NAME, COLUMN_AGE};
        Cursor cursor = db.query(TABLE_NAME, projection, null, null, null, null, null);
        return cursor;
    }

    // Update a row in the table
    public boolean updateData(int id, String name, int age) {
        SQLiteDatabase db = this.getWritableDatabase();
        ContentValues values = new ContentValues();
        values.put(COLUMN_NAME, name);
        values.put(COLUMN_AGE, age);
        String selection = COLUMN_ID + "=?";
        String[] selectionArgs = {String.valueOf(id)};
        int result = db.update(TABLE_NAME, values, selection, selectionArgs);
        db.close();
        return result > 0;
    }

    // Delete a row from the table
    public boolean deleteData(int id) {
        SQLiteDatabase db = this.getWritableDatabase();
        String selection = COLUMN_ID + "=?";
        String[] selectionArgs = {String.valueOf(id)};
        int result = db.delete(TABLE_NAME, selection, selectionArgs);
        db.close();
        return result > 0;
    }
}

您可以将此代码添加到您的项目中，并使用以下代码段执行增删改查操作：

// Instantiate the DatabaseHelper class
DatabaseHelper dbHelper = new DatabaseHelper(this);

// Insert data into the table
dbHelper.insertData("John Doe", 30);

// Retrieve data from the table
Cursor cursor = dbHelper.getData();
if(cursor.moveToFirst()) {
    do {
        int id = cursor.getInt(cursor.getColumnIndex(DatabaseHelper.COLUMN_ID));
        String name = cursor.getString(cursor.getColumnIndex(DatabaseHelper.COLUMN_NAME));
        int age = cursor.getInt(cursor.getColumnIndex(DatabaseHelper.COLUMN_AGE));
        Log.d("Database", "ID: " + id + ", Name: " + name + ", Age: " + age);
    } while(cursor.moveToNext());
}
cursor.close();

// Update a row in the table
dbHelper.updateData(1, "Jane Doe", 25);

// Delete a row from the table
dbHelper.deleteData(1);

请注意，此代码仅供参考，并且可能需要根据您的具体需求进行适当修改。希望能对您有所帮助！