在Android中删除SQLite中的行 [英] Deleting Row in SQLite in Android

问题描述

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一个并删除它；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.

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.

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
";
        }

        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);
        }
    }
}

推荐答案

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;
}

这篇关于在Android中删除SQLite中的行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！