java—在sql查询中使用“true”而不是“true”会产生意外的结果

ttcibm8c  于 2021-06-23  发布在  Mysql
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在使用entitymanager对象运行jpql查询时,我发现了一些奇怪的现象。
对于columnname或columnname,我获取布尔字段为true的任何对象的id号
plantClimbs frostresistant 或者 spicy 当plantclimps为true时,我创建的方法生成一个如下所示的查询字符串

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

当我运行这个查询时,我看到了一些意想不到的结果。它不是检索其攀缘植物字段为true的所有seedrecord id,而是获取其攀缘植物字段为false且抗冻或辛辣字段恰好为true的seedrecord的所有id。
当我删除true周围的字符时,它又开始获取正确的id。我的问题是:为什么会这样?为什么加上“真”似乎否定了一切,以至于那些攀缘植物地为假的种子记录反而被取走了呢?
以下是我的完整方法:

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;
    }
}
nvbavucw

nvbavucw1#

因为你的 climbingPlant 列是布尔的,所以mysql必须强制转换 'true' 将其与布尔值进行比较,这是(对于任何字符串都是)false。所以当你有 true 在引号中,它匹配 climbingPlant 什么时候 climbingPlant 是假的。其他列的值是不相关的。要进行演示,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

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