java.lang.IllegalArgumentException : column 'foo' does not exist android 异常

Question

许多 StackOverflow 问题都是类似的，但这不是查询字符串中的间距不正确的问题。我有两张表，一张用于对等点，一张用于消息，它具有与对等点表中的 ID 关联的外键。

这是我创建的字符串:

private static final String DATABASE_CREATE = "CREATE TABLE " + PEER_TABLE + " ("
        + PeerContract._ID    + " INTEGER PRIMARY KEY, "
        + PeerContract.NAME + " TEXT NOT NULL, "
        + PeerContract.ADDRESS  + " TEXT NOT NULL, "
        + PeerContract.PORT + " TEXT NOT NULL);";

private static final String MESSAGE_TABLE_CREATE = "CREATE TABLE " + MESSAGE_TABLE + " ("
        + MessageContract._ID + " INTEGER PRIMARY KEY, "
        + MessageContract.MESSAGE_TEXT  + " TEXT NOT NULL, "
        + MessageContract.SENDER + " TEXT NOT NULL, "
        + MessageContract.PEER_FOREIGN_KEY + " INTEGER NOT NULL, "
        + "FOREIGN KEY ("+ MessageContract.PEER_FOREIGN_KEY+") " +
        "REFERENCES "+PEER_TABLE+"("+PeerContract._ID+") ON DELETE CASCADE);";
private static final String CREATE_INDEX =  "CREATE INDEX " + INDEX + " ON " +
        MESSAGE_TABLE + "(" + MessageContract.PEER_FOREIGN_KEY + ");";

我想查询所有收到消息的列表，所以我这样做了:

public Cursor fetchAllMessages(){
    String query = "SELECT " + MESSAGE_TABLE + "." + MessageContract._ID + ", "
            + MessageContract.MESSAGE_TEXT + ", "
            + MessageContract.SENDER
            + " FROM " + MESSAGE_TABLE + " JOIN " + PEER_TABLE + " ON "
            + MESSAGE_TABLE + "." + MessageContract.PEER_FOREIGN_KEY
            + "=" + PEER_TABLE + "." + PeerContract._ID;
    return db.rawQuery(query, null);
}

这对我来说很有意义。到目前为止间距没问题，没有错误。

在我的主要 Activity 中，我有一个 SimpleCursorAdapter:

   listView = (ListView) findViewById(R.id.msgList);
    dbAdapter = new ServerDbAdapter(this);
    dbAdapter.open();
    String[] from = new String[] {PeerContract.NAME, MessageContract.MESSAGE_TEXT};
    int[] to = new int[] {android.R.id.text1, android.R.id.text2};
    cursorAdapter = new SimpleCursorAdapter(this, android.R.layout.simple_list_item_2, cursor, from, to);
    listView.setAdapter(cursorAdapter);
    cursor = dbAdapter.fetchAllMessages();
    cursorAdapter.swapCursor(cursor);

我收到“列‘名称’不存在”，这让我发疯!我在 DATABASE_CREATE 中将其正确定义为 PeerContract.NAME。我猜它的发生是因为 fetchAllMessages 但我不确定如何修复它。

Answer 1

您没有在 fetchAllMessages() 方法中选择 PeerContract.NAME, MessageContract.MESSAGE_TEXT。将其更改为:

public Cursor fetchAllMessages(){
    String query = "SELECT " + MESSAGE_TABLE + "." + MessageContract._ID + ", "
            + MessageContract.MESSAGE_TEXT + ", "
            + PeerContract.NAME + ", "
            + PeerContract.MESSAGE_TEXT + ", "
            + MessageContract.SENDER 
            + " FROM " + MESSAGE_TABLE + " JOIN " + PEER_TABLE + " ON "
            + MESSAGE_TABLE + "." + MessageContract.PEER_FOREIGN_KEY
            + "=" + PEER_TABLE + "." + PeerContract._ID;
    return db.rawQuery(query, null);
}