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Question

我的Dao文件中包含以下代码。

@Query("SELECT * FROM ${Test.TABLE_NAME} WHERE primary_key = :primaryKey LIMIT 1")
fun selectTest(primaryKey: String): Test?

问题是primaryKey是一个字符串，其中可以包含/。如Test/4。这将导致查询失败。我尝试在:primaryKey周围加上引号，但是Room不再绑定它了。我还尝试将转义的引号添加到将绑定到查询的primaryKey字符串中，但这也不起作用。

关于如何处理此问题的想法？

Answer 1

表名包含特殊字符，因此必须用SQLite和ROOM可接受的字符括起来。

在SQLITE中，您可以使用以下之一：-

`tablename` 
"tablename" 
'tablename' 
[tablename]

然而，ROOM却比较麻烦，因为它不允许您使用中间的两个。这样尝试：-

@Query("SELECT * FROM `${Test.TABLE_NAME}` WHERE primary_key = :primaryKey LIMIT 1")
fun selectTest(primaryKey: String): Test?

或

@Query("SELECT * FROM [${Test.TABLE_NAME}] WHERE primary_key = :primaryKey LIMIT 1")
fun selectTest(primaryKey: String): Test?

测试

请注意，以上是原理代码，尚未经过测试或运行，因此可能包含一些小错误。但是，为了方便起见，已经通过将代码从一个答案改编为另一个问题来测试了等效的Java代码。

使用：-

@Query("SELECT * FROM `/cards` WHERE card_name LIKE :cardName")
Cards[] getCardsByName(String cardName);

@Query("SELECT * FROM [" + GamesDatabase.TABLENAMECARDS +"] WHERE card_name LIKE :cardName")
Cards[] getFunnyCardsByName(String cardName);

GamesDatabase.TABLENAMECARDS是相同的表名，但为常量，即/ cards

以上道的用法是：-

    String cardToGet = "%/";
    Cards[] retrievedCards = mGamesDao.getCardsByName(cardToGet);
    for (Cards c: retrievedCards) {
        logCardsInfo(c,"GETCARDSBYNAME");
    }

    retrievedCards = mGamesDao.getFunnyCardsByName(cardToGet);
    for (Cards c: retrievedCards) {
        logCardsInfo(c,"GETCARDSBYFUNNYNAME");
    }

logCardsInfo方法写入卡，它的名称，值，它的ID，它的文件夹和它的类别（作为要传递的第二个参数的TAG）。

其中Cards包含一包纸牌（带有一个称为ooops的额外花色，不适合等同于Category，每个Category的文件夹中有两个，但normalcards文件夹中有7个），但是卡的名称为7是7 /而不是7，所以按照：-

2019-09-16 15:01:46.084 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 10
        In Folder NormalCards
            In Category Spades
2019-09-16 15:01:46.089 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 23
        In Folder NormalCards
            In Category Hearts
2019-09-16 15:01:46.094 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 36
        In Folder NormalCards
            In Category Clubs
2019-09-16 15:01:46.101 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 49
        In Folder NormalCards
            In Category Diamonds
2019-09-16 15:01:46.107 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYNAME: Card Name is 7/
        Value is 7
        CardID is 62
        In Folder NormalCards
            In Category ooops
2019-09-16 15:01:46.110 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 10
        In Folder NormalCards
            In Category Spades
2019-09-16 15:01:46.114 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 23
        In Folder NormalCards
            In Category Hearts
2019-09-16 15:01:46.118 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 36
        In Folder NormalCards
            In Category Clubs
2019-09-16 15:01:46.121 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 49
        In Folder NormalCards
            In Category Diamonds
2019-09-16 15:01:46.122 19140-19140/aso.so57943963foreignkeys D/GETCARDSBYFUNNYNAME: Card Name is 7/
        Value is 7
        CardID is 62
        In Folder NormalCards
            In Category ooops

在会议室数据库查询中转义特殊字符

1 个答案:

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