Deleting Row in SQLite in Android

问题

This might be a dumb question, but I\'m new to SQLite and I can\'t seem to figure this out. I have 1 table that has columns KEY_ROWID, KEY_NAME, KAY_LATITUDE, and KEY_LONGITUDE. I want the user to be able to select one and delete it; Can anyone give me a direction to start in? My question is in the actual deletion of the row given only its name.

Relevant code:

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);
        }
    }
}

回答1:

You can try like this:

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

or

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

回答2:

Try like that may you get your solution

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

回答3:

it's better to use whereargs too;

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

this is like useing this command:

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

and using delete function in such way is good because it removes sql injections.

回答4:

Till i understand your question,you want to put two conditions to select a row to be deleted.for that,you need to do:

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);
      */  

}

回答5:

Try this code

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

回答6:

Try this code...

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

回答7:

This works perfectly:

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

You can also refer to this example.

回答8:

Guys this is a generic method you can use for all your tables, Worked perfectly in my case.

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

回答9:

if you are using SQLiteDatabase then there is a delete method

Definition of Delete

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

Example Implementation

Now we can write a method called delete with argument as name

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

if you want to delete all records then just pass null to the above method,

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

Source Of Information

回答10:

To delete rows from a table, you need to provide selection criteria that identify the rows to the delete() method. The mechanism works the same as the selection arguments to the query() method. It divides the selection specification into a selection clause(where clause) and selection arguments.

    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.

The return value for the delete() method indicates the number of rows that were deleted from the database.

回答11:

Guys if above solutions don't work for you then try this one also because it worked for me.

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

回答12:

Works great!

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

回答13:

Try this one:

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

回答14:

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

回答15:

You can do something like this, sharing my working code snippet

Make sure query is like this

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();
        }

回答16:

Try the below code-

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.
}

来源：https://stackoverflow.com/questions/7510219/deleting-row-in-sqlite-in-android