java - 在SQL查询中使用'true'而不是true会产生意外结果

在使用entityManager对象运行jpql查询时，发现了一些奇怪的东西。

我获取列名plantClimbs frostresistant或spicy的布尔字段为true的所有对象的ID号

当plantClimbs为true时，我制作的方法将使查询字符串看起来像这样

select u.id from SeedRecord u WHERE u.climbingPlant = 'true'

当我运行此查询时，我看到一些意外的结果。它不会获取所有climbingPlant字段为true的SeedRecord id，而是获取其climbingPlant字段为false且frostResistant或Spicy字段为true的所有种子记录的id。

当我删除'字符周围true时，它开始再次获取正确的ID。我的问题是：为什么会这样？为什么将'设置为true似乎会否定一切，以便实际上取回攀爬字段为false的种子记录？

这是我的完整方法：

private Set<Long> findAllSeedRecordsByKeywordsOrBooleans(Set<String> checkKeywords, boolean plantClimbs, boolean teaPlant, boolean spicy){
    if (checkKeywords.isEmpty()
            && !plantClimbs
            && !spicy
            && !teaPlant) return Collections.EMPTY_SET;
    Set<String> availablePlantTypes = new HashSet<>();
    Set<String> availableProduceTypes = new HashSet<>();
    log.info("fetching entitymanager");
    EntityManager entityManager = seedRecordDao.getEntityManager();
    Map<String,Set<String>> containsProduceNameKeyword = new HashMap<>();
    Map<String,Set<PlantType>> containsPlantTypeKeyword = new HashMap<>();
    Map<String,Set<ProduceType>> containsProduceTypeKeyword = new HashMap<>();
    Set<String> searchProduceNames = new HashSet<>();
    Set<PlantType> searchPlantTypes = new HashSet<>();
    Set<ProduceType> searchProduceTypes = new HashSet<>();
    boolean hasPriorCondition = false;
    boolean produceNamesConditionApplied = false;
    boolean produceTypesConditionApplied = false;
    boolean plantTypesConditionApplied = false;

    StringBuilder filterQuery = new StringBuilder("select u.id from SeedRecord u WHERE ");
    if(!checkKeywords.isEmpty()) {
        log.info("getting the producenames");
        Set<String> availableProduceNames = seedRecordDao.getProduceNames()
                .stream().map(ProduceName::getProduceName).collect(Collectors.toSet());
        for (PlantType plantType : PlantType.values())
            availablePlantTypes.add(plantType.toString());
        for (ProduceType produceType : ProduceType.values())
            availableProduceTypes.add(produceType.toString());
        for (String keyword : checkKeywords) {
            if (availableProduceNames.contains(keyword)) {
                searchProduceNames.add(keyword);
                if (!produceNamesConditionApplied) {
                    if (!hasPriorCondition) {
                        filterQuery.append("u.produceName IN :produceNames ");
                        hasPriorCondition = true;
                    } else
                        filterQuery.append("OR u.produceName IN :produceNames ");
                    produceNamesConditionApplied = true;
                }
            } else if (availablePlantTypes.contains(keyword)) {
                searchPlantTypes.add(PlantType.valueOf(keyword));
                if (!plantTypesConditionApplied) {
                    if (!hasPriorCondition) {
                        filterQuery.append("u.plantType IN :plantTypes ");
                        hasPriorCondition = true;
                    } else
                        filterQuery.append("OR u.plantType IN :plantTypes ");
                    plantTypesConditionApplied = true;
                }
            } else if (availableProduceTypes.contains(keyword)) {
                searchProduceTypes.add(ProduceType.valueOf(keyword));
                if (!produceTypesConditionApplied) {
                    if (!hasPriorCondition) {
                        filterQuery.append("u.produceType IN :produceTypes ");
                        hasPriorCondition = true;
                    } else
                        filterQuery.append("OR u.produceType IN :produceTypes ");
                    produceTypesConditionApplied = true;
                }
            }
        }

        if (!searchProduceNames.isEmpty())
            containsProduceNameKeyword.put("produceNames", searchProduceNames);
        if (!searchProduceTypes.isEmpty())
            containsProduceTypeKeyword.put("produceTypes", searchProduceTypes);
        if (!searchPlantTypes.isEmpty())
            containsPlantTypeKeyword.put("plantTypes", searchPlantTypes);
    }

    if(plantClimbs)
        if (!hasPriorCondition) {
            filterQuery.append("u.climbingPlant = 'true' ");
            hasPriorCondition = true;
        }
        else
            filterQuery.append("OR u.climbingPlant = 'true' ");
    if(teaPlant)
        if (!hasPriorCondition) {
            filterQuery.append("u.teaPlant = 'true' ");
            hasPriorCondition = true;
        }
        else
            filterQuery.append("OR u.teaPlant = 'true' ");
    if(spicy)
        if (!hasPriorCondition) {
            filterQuery.append("u.spicy = 'true' ");
        }
        else
            filterQuery.append("OR u.spicy = 'true' ");
    try {
        log.info("preparing query");
        log.info(filterQuery.toString());
        TypedQuery<Long> query = entityManager.createQuery(filterQuery.toString(), Long.class);
        if (!containsProduceNameKeyword.isEmpty())
            containsProduceNameKeyword.forEach((parameter, input) -> query.setParameter(parameter, input));
        if (!containsPlantTypeKeyword.isEmpty())
            containsPlantTypeKeyword.forEach((parameter, input) -> query.setParameter(parameter, input));
        if (!containsProduceTypeKeyword.isEmpty())
            containsProduceTypeKeyword.forEach((parameter, input) -> query.setParameter(parameter, input));
        log.info("sending to database NOW");
        return new HashSet<>(query.getResultList());
    }
    catch(Exception e){
        throw e;
    }
}

最佳答案

这是因为您的climbingPlant列是布尔值，因此MySQL必须将'true'强制转换为布尔值才能与它进行比较，这（对于任何字符串而言）都是false。因此，当您使用true引号时，当climbingPlant为false时，它与climbingPlant匹配。其他列的值无关紧要。对于演示，请尝试以下操作：

select 'true' = true, 'true' = false, 'anything' = false

输出：

'true' = true   'true' = false  'anything' = false
0               1               1