使用列名删除一行 - SQlite (SQLiteOpenHelper Android)

Question

我需要删除数据库（SQLite）中的一行。

我正试图使用文件名删除一行。文件是数据库列中的一个字段。

public void deleteRow (String file){
    SQLiteDatabase db = this.getWritableDatabase();
    db.delete("checkList", "DELETE FROM checkList Where file = "+file, null);
}

我得到的是

进程：com.example.operachecklist，PID：29351 android.database.sqlite.SQLiteException：靠近 "DELETE"：语法错误（代码1 SQLITE_ERROR[1]）。，在编译时。DELETE FROM checkList WHERE DELETE FROM checkList Where file = SE 062 Merlo20:05:23:12.txt。

这是我实现的类代码。

class MyDB extends SQLiteOpenHelper {

    private static final int VERSION_BASEDATOS = 1;

    private static final String NAME = "checkList.db";

    private static final String TABLA_CHECK_LIST = "CREATE TABLE IF NOT EXISTS checkList" +
            "(id INTEGER PRIMARY KEY AUTOINCREMENT, file TEXT, se TEXT, date TEXT, aux TEXT)";

    public MyDB(Context context) {
        super(context, NAME, null, VERSION_BASEDATOS);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL(TABLA_CHECK_LIST);
    }

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

    public boolean deleteDB(Context context) {
        return context.deleteDatabase(NAME);
    }

    public void insert(String file, String se, String date, String aux) {
        SQLiteDatabase db = getWritableDatabase();
        if (db != null) {
            ContentValues valores = new ContentValues();
            valores.put("file", file);
            valores.put("se", se);
            valores.put("date", date);
            valores.put("aux", aux);
            db.insert("checkList", null, valores);
            db.close();
        }
    }

    public List<String> loadHandler() {
        List<String> list = new ArrayList<String>();
        String query = "Select*FROM checkList";
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(query, null);
        while (cursor.moveToNext()) {
            int result_0 = cursor.getInt(0);
            String result_1 = cursor.getString(1);
            String result_2 = cursor.getString(2);
            String result_3 = cursor.getString(3);
            String result_4 = cursor.getString(4);

            list.add(result_1 + "%:&" + result_2 + "%:&" + result_3 + "%:&" + result_4);
        }
        cursor.close();
        db.close();
        return list;
    }

    public int getRowCount() {
        String query = "Select*FROM checkList";
        SQLiteDatabase db = this.getWritableDatabase();
        Cursor cursor = db.rawQuery(query, null);
        return cursor.getCount();
    }

    public void deleteFirstRow() {
        SQLiteDatabase db = this.getWritableDatabase();
        String where = "id < (select id from checkList order by id limit 15, 1)";
        db.delete("checkList", where, null);
    }

    public void orderIt() {
        SQLiteDatabase db = this.getWritableDatabase();
        db.execSQL("VACUUM");
    }

    public String getLastHash() {
        SQLiteDatabase db = this.getWritableDatabase();
        String query = "Select*FROM checkList";
        Cursor cursor = db.rawQuery(query, null);
        cursor.moveToLast();
        return cursor.getString(1);
    }

    public void deleteRow(String file) {
        SQLiteDatabase db = this.getWritableDatabase();
        db.delete("checkList", "DELETE FROM checkList Where file = " + file, null);
    }
}

Answer 1

问题是在第2个参数 delete() 你使用完整的 sql 语句，这是不需要的，而且你将变量 file 到 sql 语句的字符串中，而不需要用单引号包围。但即使你这样做了，这也不是安全和推荐的方式。将参数 file 在方法的3d参数中 delete() 并使用 ? 占位符，它将被sql语句的值替换为 file，适当引用，当语句将被解析。

db.delete("checkList", "file = ?", new String[] {file});

第二参数 delete() 是 WHERE 子句，不含关键字 WHERE.