在 Android 中删除 SQLite 中的行

Question

这可能是一个愚蠢的问题，但我是 SQLite 的新手，我似乎无法弄清楚这一点。我有 1 个表，其中包含 KEY_ROWID、KEY_NAME、KAY_LATITUDE 和 KEY_LONGITUDE 列。我希望用户能够选择并删除它；谁能给我一个开始的方向？我的问题是实际删除仅给出其名称的行。

相关代码：

public class BeaconDatabase {

    public static final String KEY_ROWID = "_id";
    public static final String KEY_NAME = "beacon_name";
    public static final String KEY_LATITUDE = "beacon_lat";
    public static final String KEY_LONGITUDE = "beacon_lon";

    private static final String DATABASE_NAME ="BeaconDatabase";
    private static final String DATABASE_TABLE ="beaconTable";
    private static final int DATABASE_VERSION = 1;

    private DbHelper helper;
    private final Context context;
    private SQLiteDatabase db;

    public BeaconDatabase(Context context) {
        this.context = context;
    }

    public BeaconDatabase open() {
        helper = new DbHelper(this.context);
        db = helper.getWritableDatabase();
        return this;
    }

    public void close() {
        helper.close();
    }

    public long createEntry(String name, Double lat, Double lon) {
        ContentValues cv = new ContentValues();
        cv.put(KEY_NAME, name);
        cv.put(KEY_LATITUDE, lat);
        cv.put(KEY_LONGITUDE, lon);
        return db.insert(DATABASE_TABLE, null, cv);
    }

    public void deleteEntry(long row) {

              // Deletes a row given its rowId, but I want to be able to pass
              // in the name of the KEY_NAME and have it delete that row.
              //db.delete(DATABASE_TABLE, KEY_ROWID + "=" + row, null);
    }

    public String getData() {
        String[] columns = { KEY_ROWID, KEY_NAME, KEY_LATITUDE, KEY_LONGITUDE };
        Cursor cursor = db.query(DATABASE_TABLE, columns, null, null, null, null, null);
        String result = "";

        int iRow = cursor.getColumnIndex(KEY_ROWID);
        int iName = cursor.getColumnIndex(KEY_NAME);
        int iLat = cursor.getColumnIndex(KEY_LATITUDE);
        int iLon = cursor.getColumnIndex(KEY_LONGITUDE);

        for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()) {
            result += cursor.getString(iRow) + ": " + cursor.getString(iName) + " - " + cursor.getDouble(iLat) + " latitude " + cursor.getDouble(iLon) + " longitude\n";
        }

        return result;

    }

    private static class DbHelper extends SQLiteOpenHelper {

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

        @Override
        public void onCreate(SQLiteDatabase db) {
            db.execSQL("CREATE TABLE " +  DATABASE_TABLE + " (" + 
                    KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                    KEY_NAME + " TEXT NOT NULL, " +
                    KEY_LATITUDE + " DOUBLE, " +
                    KEY_LONGITUDE + " DOUBLE);"
            );
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
            onCreate(db);
        }
    }
}

Answer 1

你可以这样试试：

 //---deletes a particular title---
public boolean deleteTitle(String name) 
{
    return db.delete(DATABASE_TABLE, KEY_NAME + "=" + name, null) > 0;
}

或

public boolean deleteTitle(String name) 
{
    return db.delete(DATABASE_TABLE, KEY_NAME + "=?", new String[]{name}) > 0;
}

Answer 2

这样尝试可能会得到您的解决方案

String table = "beaconTable";
String whereClause = "_id=?";
String[] whereArgs = new String[] { String.valueOf(row) };
db.delete(table, whereClause, whereArgs);

Answer 3

最好也使用 whereargs；

db.delete("tablename","id=? and name=?",new String[]{"1","jack"});

这就像使用这个命令：

delete from tablename where id='1' and name ='jack'

并且以这种方式使用删除功能很好，因为它可以删除 sql 注入。

Answer 4

在我理解你的问题之前，你想设置两个条件来选择要删除的行。为此，你需要这样做：

public void deleteEntry(long row,String key_name) {

      db.delete(DATABASE_TABLE, KEY_ROWID + "=" + row + " and " + KEY_NAME + "=" + key_name, null);

      /*if you just have key_name to select a row,you can ignore passing rowid(here-row) and use:

      db.delete(DATABASE_TABLE, KEY_NAME + "=" + key_name, null);
      */  

}

Answer 5

试试这个代码

public void deleteRow(String value)
{
SQLiteDatabase db = this.getWritableDatabase();       
db.execSQL("DELETE FROM " + TABLE_NAME+ " WHERE "+COlUMN_NAME+"='"+value+"'");
db.close();
}

Answer 6

试试这个代码...

private static final String mname = "'USERNAME'";
public void deleteContact()
{
    db.delete(TABLE_CONTACTS, KEY_NAME + "=" + mname, null);
}

Answer 7

这很好用：

public boolean deleteSingleRow(String rowId) 
{
    return db.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0;
}

您也可以参考this example。

Answer 8

如果你使用的是 SQLiteDatabase 那么有一个删除方法

删除的定义

int delete (String table, String whereClause, String[] whereArgs)

示例实现

现在我们可以编写一个名为delete with argument作为名称的方法

public void delete(String value) {
    db.delete(DATABASE_TABLE, KEY_NAME + "=?", new String[]{String.valueOf(value)});
}

如果您想删除所有记录，则只需将 null 传递给上述方法，

public void delete() {
    db.delete(DATABASE_TABLE, null, null);
}

Source Of Information

Answer 9

伙计们，这是一种可用于所有表格的通用方法，在我的情况下完美运行。

public void deleteRowFromTable(String tableName, String columnName, String keyValue) {
    String whereClause = columnName + "=?";
    String[] whereArgs = new String[]{String.valueOf(keyValue)};
    yourDatabase.delete(tableName, whereClause, whereArgs);
}

Answer 10

要从表中删除行，您需要向delete() 方法提供标识行的选择条件。该机制与query() 方法的选择参数相同。它将选择规范分为选择子句（where 子句）和选择参数。

    SQLiteDatabase db  = this.getWritableDatabase();
     // Define 'where' part of query.
    String selection = Contract.COLUMN_COMPANY_ID + " =?  and "
                       + Contract.CLOUMN_TYPE +" =? ";
   // Specify arguments in placeholder order.
    String[] selectionArgs = { cid,mode };
    // Issue SQL statement.
    int deletedRows = db.delete(Contract.TABLE_NAME, 
                       selection, selectionArgs);
    return deletedRows;// no.of rows deleted.

delete() 方法的返回值表示从数据库中删除的行数。

Answer 11

如果上述解决方案对您不起作用，那么请尝试这个，因为它对我有用。

public boolean deleteRow(String name) 
{
    return db.delete(DATABASE_TABLE, KEY_NAME + "='" + name +"' ;", null) > 0;
}

Answer 12

效果很好！

public void deleteNewMelk(String melkCode) {
    getWritableDatabase().delete(your_table, your_column +"=?", new String[]{melkCode});
}

Answer 13

试试这个：

public void deleteEntry(long rowId) {
    database.delete(DATABASE_TABLE , KEY_ROWID 
        + " = " + rowId, null);}

Answer 14

public boolean deleteRow(long l) {
    String where = "ID" + "=" + l;
    return db.delete(TABLE_COUNTRY, where, null) != 0;
}

Answer 15

你可以这样做，分享我的工作代码 sn-p

确保查询是这样的

DELETE FROM tableName WHERE KEY__NAME = 'parameterToMatch'

public void removeSingleFeedback(InputFeedback itemToDelete) {
            //Open the database
            SQLiteDatabase database = this.getWritableDatabase();

            //Execute sql query to remove from database
            //NOTE: When removing by String in SQL, value must be enclosed with ''
            database.execSQL("DELETE FROM " + TABLE_FEEDBACKS + " WHERE "
                    + KEY_CUSTMER_NAME + "= '" + itemToDelete.getStrCustName() + "'" +
                    " AND " + KEY_DESIGNATION + "= '" + itemToDelete.getStrCustDesignation() + "'" +
                    " AND " + KEY_EMAIL + "= '" + itemToDelete.getStrCustEmail() + "'" +
                    " AND " + KEY_CONTACT_NO + "= '" + itemToDelete.getStrCustContactNo() + "'" +
                    " AND " + KEY_MOBILE_NO + "= '" + itemToDelete.getStrCustMobile() + "'" +
                    " AND " + KEY_CLUSTER_NAME + "= '" + itemToDelete.getStrClusterName() + "'" +
                    " AND " + KEY_PRODUCT_NAME + "= '" + itemToDelete.getStrProductName() + "'" +
                    " AND " + KEY_INSTALL_VERSION + "= '" + itemToDelete.getStrInstalledVersion() + "'" +
                    " AND " + KEY_REQUIREMENTS + "= '" + itemToDelete.getStrRequirements() + "'" +
                    " AND " + KEY_CHALLENGES + "= '" + itemToDelete.getStrChallenges() + "'" +
                    " AND " + KEY_EXPANSION + "= '" + itemToDelete.getStrFutureExpansion() + "'" +
                    " AND " + KEY_COMMENTS + "= '" + itemToDelete.getStrComments() + "'"
            );

            //Close the database
            database.close();
        }

Answer 16

试试下面的代码-

mSQLiteDatabase = getWritableDatabase();//To delete , database should be writable.
int rowDeleted = mSQLiteDatabase.delete(TABLE_NAME,id + " =?",
                    new String[] {String.valueOf(id)});
mSQLiteDatabase.close();//This is very important once database operation is done.
if(rowDeleted != 0){
    //delete success.
} else {
    //delete failed.
}

Answer 17

对我有用的唯一方法是这个

fun removeCart(mCart: Cart) {
    val db = dbHelper.writableDatabase
    val deleteLineWithThisValue = mCart.f
    db.delete(cons.tableNames[3], Cart.KEY_f + "  LIKE  '%" + deleteLineWithThisValue + "%' ", null)
}


class Cart {
    var a: String? = null
    var b: String? = null
    var c: String? = null
    var d: String? = null
    var e: Int? = null
    var f: String? = null

companion object {
    // Labels Table Columns names
    const val rowIdKey = "_id"
    const val idKey = "id"
    const val KEY_a = "a"
    const val KEY_b = "b"
    const val KEY_c = "c"
    const val KEY_d = "d"
    const val KEY_e = "e"
    const val KEY_f = "f"
   }
}

object cons {
    val tableNames = arrayOf(
            /*0*/ "shoes",
            /*1*/ "hats",
            /*2*/ "shirt",
            /*3*/ "car"
         )
 }

Answer 18

但接受的答案对我不起作用。我认为字符串应该是在 SQL 中，字符串必须被引用。所以，就我而言，这对我来说与接受的答案相反：

 database.delete(TABLE_DAILY_NOTES, WORK_ENTRY_CLUMN_NAME + "='" + workEntry+"'", null);