如何使用Sqiltehelper在Android中删除表和数据库

我创建了一个类调用 DatabaseHandler来扩展sqliteOpenHelper.我想解释删除的数据库或表上的按钮点击.我必须传递给调用方法的参数是什么？以下是代码供参考：

public class DatabaseHandler extends sqliteOpenHelper
{

 // All Static variables
// Database Version
public static final int DATABASE_VERSION =1;

// Database Name
public static final String DATABASE_NAME = "EmployeeDB";

// Contacts table name
public static final String TABLE_CONTACTS = "contacts";

// Contacts Table Columns names
private static final String KEY_ID = "id";
private static final String KEY_NAME = "name";
private static final String KEY_PH_NO = "phone_number";
public DatabaseHandler(Context context)
{
    super(context,DATABASE_NAME,null,DATABASE_VERSION);
}


@Override
public void onCreate(sqliteDatabase db)
{
    // Todo Auto-generated method stub

    String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
    + KEY_ID + " INTEGER PRIMARY KEY," + KEY_NAME + " TEXT,"
    + KEY_PH_NO + " TEXT" + ")";
    db.execsql(CREATE_CONTACTS_TABLE);

}

@Override
public void onUpgrade(sqliteDatabase db,int oldVersion,int newVersion)
{
    // Todo Auto-generated method stub
     db.execsql("DROP TABLE IF EXISTS " + TABLE_CONTACTS);

        // Create tables again
        onCreate(db);

}

 /**
 * All CRUD(Create,Read,Update,Delete) Operations
 */

// Adding new contact
void addContact(Contact contact) {
    sqliteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_NAME,contact.getName()); // Contact Name
    values.put(KEY_PH_NO,contact.getPhoneNumber()); // Contact Phone

    // Inserting Row
    db.insert(TABLE_CONTACTS,values);
    db.close(); // Closing database connection
}

// Getting single contact
Contact getContact(int id) {
    sqliteDatabase db = this.getReadableDatabase();

    Cursor cursor = db.query(TABLE_CONTACTS,new String[] { KEY_ID,KEY_NAME,KEY_PH_NO },KEY_ID + "=?",new String[] { String.valueOf(id) },null);
    if (cursor != null)
        cursor.movetoFirst();

    Contact contact = new Contact(id,cursor.getString(1),cursor.getString(2));
    // return contact
    return contact;
}

// Getting All Contacts
public List<Contact> getAllContacts() {
    List<Contact> contactList = new ArrayList<Contact>();
    // Select All Query
    String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS;

    sqliteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery,null);

    // looping through all rows and adding to list
    if (cursor.movetoFirst()) {
        do {
            Contact contact = new Contact();
            contact.setID(Integer.parseInt(cursor.getString(0)));
            contact.setName(cursor.getString(1));
            contact.setPhoneNumber(cursor.getString(2));
            // Adding contact to list
            contactList.add(contact);
        } while (cursor.movetoNext());
    }

    // return contact list
    return contactList;
}

// Updating single contact
public int updateContact(Contact contact) {
    sqliteDatabase db = this.getWritableDatabase();

    ContentValues values = new ContentValues();
    values.put(KEY_NAME,contact.getName());
    values.put(KEY_PH_NO,contact.getPhoneNumber());

    // updating row
    return db.update(TABLE_CONTACTS,values,KEY_ID + " = ?",new String[] { String.valueOf(contact.getID()) });
}

// Deleting single contact
public void deleteContact(Contact contact) {
    sqliteDatabase db = this.getWritableDatabase();
    db.delete(TABLE_CONTACTS,new String[] { String.valueOf(contact.getID()) });
    db.close();
}

// Getting contacts Count
public int getContactsCount() {
    String countQuery = "SELECT  * FROM " + TABLE_CONTACTS;
    sqliteDatabase db = this.getReadableDatabase();
    Cursor cursor = db.rawQuery(countQuery,null);
    cursor.close();

    // return count
    return cursor.getCount();
}
public void DeleteDatabase(sqliteDatabase db,String table)
{


    db.execsql("DELETE FROM " + table);
   db.close();
}

}

解决方法

很难回答没有更多的上下文,但最终的sqlite查询将是：

db.execsql("DROP TABLE IF EXISTS tablename");

其中db是对sqliteDatabase对象的引用.

并删除数据库

context.deleteDatabase(DATABASE_NAME);