如何从sql查询中跳过元组结果中的索引 [英] how to skip an index in a tuple result from a sql query

问题描述

不幸的是，我需要为我的项目的一部分使用'native'sql查询来从未映射表中返回元组。

I unfortunately need to use 'native' sql queries for a portion of my project to return tuples from unmapped tables.

我有一堆查询每行返回相同数量的值，然后进入处理方法将其转换为对象。

I have a bunch of queries which are supposed to return the same number of values per row and then go into a processing method to turn them into objects.

例如：

List<Object[]> list = ...;
List<MyBean> beans = ...;

SQLQuery qry1 = session.createSQLQuery(...);
SQLQuery qry2 = session.createSQLQuery(...);
SQLQuery qry3 = session.createSQLQuery(...);

list.addAll(qry1.list());
list.addAll(qry2.list());
list.addAll(qry3.list());

for(Object[] tuple : list)
{
    MyBean bean = new MyBean();
    bean.setSomething0(tuple[0]);
    bean.setSomething1(tuple[1]);
    bean.setSomething2(tuple[2]);
    bean.setSomething3(tuple[3]);
    beans.add(bean);
}

现在，我的问题是 qry3 没有相关的列来填充元组第二个索引处的值，但是填充第三个索引。我需要修改它的查询，以便用 null 或以某种方式填充元组。

now, my problem is that qry3 does not have a relevent column to populate the value at the 2nd index of the tuple, but does populate the 3rd index. I need to modify it's query so that it populates the tuple with null or "" somehow.

我试过select a，b，null，d和select a，b， ''，d但是这两个都会导致异常：

I've tried "select a, b, null, d" and "select a, b, '', d" however both of these cause an exception:

org.hibernate.MappingException: No Dialect mapping for JDBC type: 1111
    at org.hibernate.dialect.TypeNames.get(TypeNames.java:56)
    at org.hibernate.dialect.TypeNames.get(TypeNames.java:81)
    at org.hibernate.dialect.Dialect.getHibernateTypeName(Dialect.java:370)
    at org.hibernate.loader.custom.CustomLoader$Metadata.getHibernateType(CustomLoader.java:559)
    at org.hibernate.loader.custom.CustomLoader$ScalarResultColumnProcessor.performDiscovery(CustomLoader.java:485)
    at org.hibernate.loader.custom.CustomLoader.autoDiscoverTypes(CustomLoader.java:501)
    at org.hibernate.loader.Loader.getResultSet(Loader.java:1796)
    at org.hibernate.loader.Loader.doQuery(Loader.java:674)
    at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236)
    at org.hibernate.loader.Loader.doList(Loader.java:2213)
    at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104)
    at org.hibernate.loader.Loader.list(Loader.java:2099)
    at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289)
    at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1695)
    at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142)
    at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:152)

那么我该如何告诉我的查询在这种情况下跳过一个索引？

so how do i tell my query to skip an index in this case?

推荐答案

您可以尝试将其转换为预期的类型：

You can try to cast it to the expected type:

select a, b, cast(null as varchar), d

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