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使用 Sqiltehelper 如何删除表格和数据库

我创建了一个类调用 DatabaseHandler 继承SQLiteOpenHelper。我想删除数据库或者在点击按钮时删除表格,如何处理那些我调用方法而传递的参数?
供参考的代码:
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, null, 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, null, null, 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 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, KEY_ID + " = ?",
        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();
}

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a123456678 2016-07-18 14:44:52 2598 0
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  • SQLiteOpenHelper.getWritableDatabase can get the SQLiteDatabase class, SQLiteDatabase.delete (String table, String whereClause, String[] whereArgs)
    可以删除表格。
    如果你想删除数据库,你可以直接删除数据库文件。路径是:

    /data/data/package_name/databases/db_name

    2019-07-17 19:57:54
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