Question

以下是我用来清除数据库中所有数据的代码

public Cursor readEntry() {

        SQLiteDatabase db = helper.getWritableDatabase();

        String[] allColumns = new String[] { data.NAME,
                data._STATUS, data.WEIGHT, data.DATE};

        Cursor c = db.query(data.TABLE_NAME, allColumns, null, null, null,
                null, null);

        if (c != null) {
            c.moveToFirst();
        }
        return c;

    }

    public boolean deleteRow(long id) {

        SQLiteDatabase db = helper.getWritableDatabase();
        String where = data.UID + "=" + id;
        return db.delete(data.TABLE_NAME, where, null) != 0;
    }

    public void DeleteAll(){

        Cursor c = readEntry();
        long id = c.getColumnIndexOrThrow(data.UID);
        if (c.moveToFirst()) {
            do {
                deleteRow(c.getLong((int) id));
            } while (c.moveToNext());
        }
        c.close();

    }

我的问题是，如何使用NAME而不是使用ID，如何调用String方法？上面的代码只能调用方法data.DeleteAll（）;但是在String情况下，我该怎么称呼它？

Answer 1

使用此：

public boolean deleteRow(String name) {

    SQLiteDatabase db = helper.getWritableDatabase();
    String where = data.NAME + "=" + name;
    return db.delete(data.TABLE_NAME, where, null) != 0;
}

public void DeleteAllUsingNames(){

    Cursor c = readEntry();
    long index = c.getColumnIndexOrThrow(data.NAME);
    if (c.moveToFirst()) {
        do {
            deleteRow(c.getString((int) index);
        } while (c.moveToNext());
    }
    c.close();

}

Answer 2

您将采取以下措施：

public boolean deleteRow(String name) {
    SQLiteDatabase db = helper.getWritableDatabase();
    String where = data.NAME + "=" + name;
    return db.delete(data.TABLE_NAME, where, null) != 0;
}

Answer 3

只需将id替换为name，即可：

 public Cursor readEntry() {

            SQLiteDatabase db = helper.getWritableDatabase();

            String[] allColumns = new String[] { data.NAME,
                    data._STATUS, data.WEIGHT, data.DATE};

            Cursor c = db.query(data.TABLE_NAME, allColumns, null, null, null,
                    null, null);

            if (c != null) {
                c.moveToFirst();
            }
            return c;

        }

        public boolean deleteRow(String name) {

            SQLiteDatabase db = helper.getWritableDatabase();
            String where = data.NAME + " = " + "'" + name + "'";
            return db.delete(data.TABLE_NAME, where, null) != 0;
        }

        public void DeleteAll(){

            Cursor c = readEntry();
            long id = c.getColumnIndexOrThrow(data.NAME);
            if (c.moveToFirst()) {
                do {
                    deleteRow(c.getString((int) id));
                } while (c.moveToNext());
            }
            c.close();

        }

使用名称而不是ID删除行

3 个答案: