假设我有一个序列，称为TEST_SEQ什么是选择下一个值的正确方法是什么？

虽然 documentation 表示：

序列的下一个值可以包含在SELECT，INSERT和UPDATE语句如下例所示：

  SELECT [...，] NEXT VALUE FOR< sequencename> [，...] FROM< tablename>; 
 

正确的方式（因为更简单，因为不涉及表像HSQLDB不具备的DUAL DUAL表一样）：

 调用[sequence_name]的下一个值; 
 

这出现在 1.7.2 ，这实际上Hibernate是如何处理最近的 HSQLDialect Hibernate Core版本（请参阅 HHH-2839 ）。

事实上，这就是我在 HSQLDialect 中看到的 hibernate-core- 3.3.0.SP1.jar ：

  public String getSequenceNextValString（String sequenceName）{
返回call next value for+ sequenceName; 





 $ b 
所以我的建议是：升级到更新版本的Hibernate，你很可能使用Hibernate Core 3.2.5或更高版本。
 
suppose i have a sequence, called TEST_SEQ
what would be the correct way of selecting its next value ?
this does not work:
select next value for TEST_SEQ
probably because it expects a "FROM" clause.
looking at HSQLDialect.getSequenceNextValString() in hibernate i see this:
"select next value for " + sequenceName + " from dual_" + sequenceName
which in my case would result in something like:
select next value for TEST_SEQ from dual_TEST_SEQ
which does not work for 2.0.0-rc8 (i only assume this works in pre-2.0 versions - havent verified)
I've come across a solution that involves creating a simple table with 1 row called DUAL, in which case this will work (oracle style):
select next value for TEST_SEQ from DUAL
but hsqldb does not come with this table out of the box, and im not sure how i can get hibernate to generate such a table on "first boot".

Im thinking there has to be a way to get the next value for a sequence out of the box and im just missing it.
any ideas ?



  
suppose i have a sequence, called TEST_SEQ what would be the correct way of selecting its next value ?

While the documentation says:

  
The next value for a sequence can be included in SELECT, INSERT and UPDATE statements as in the following example:
SELECT [...,] NEXT VALUE FOR <sequencename> [, ...] FROM <tablename>;




the "correct" way (because simpler, because not involving a table like a dumb DUAL table that HSQLDB doesn't have) would be:
call NEXT VALUE FOR [sequence_name];

This appeared in 1.7.2 and this his actually how Hibernate handles sequences in the HSQLDialect of "recent" versions of  Hibernate Core (see HHH-2839). 

And indeed, this is what I see in the HSQLDialect of hibernate-core-3.3.0.SP1.jar:
public String getSequenceNextValString(String sequenceName) {
    return "call next value for " + sequenceName;
}

So my advice is: upgrade to a newer version of Hibernate, you are very likely using Hibernate Core 3.2.5 or prior.