如何通过 NHibernate 从 oracle 序列中获取 NextVal
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How do I get the NextVal from an oracle Sequence thru NHibernate
提问by trainer
I am working on c# .net 4.0 and using NHibernate to talk with an Oracle DB. You would think something as simple as this is already addressed somewhere but sadly its not. I need the NextVal from an Oracle sequence. I do not need to insert it a database as part of an Id or Primary key. I just need to use the next val on the c# side.
我正在使用 c# .net 4.0 并使用 NHibernate 与 Oracle DB 对话。你会认为像这样简单的事情已经在某处解决了，但遗憾的是它没有。我需要 Oracle 序列中的 NextVal。我不需要将它插入数据库作为 Id 或主键的一部分。我只需要在 c# 端使用下一个 val。
Can somebody help me out with xml mapping and C# file(or a link) to achieve this.
有人可以帮助我使用 xml 映射和 C# 文件（或链接）来实现这一点。
Thanks.
谢谢。
Something like
就像是
int NextValueOfSequence = GetNextValueofSequence();
public int GetNextValueOfSequence()
{
// Access NHibernate to return the next value of the sequence.
}
回答by Petr Kozelek
Mapping:
映射：
<sql-query name="GetSequence" read-only="true">
<return-scalar type="Int64"/>
<![CDATA[
SELECT SeqName.NEXTVAL from DUAL;
]]>
</sql-query>
Code:
代码：
Int64 nextValue = session.GetNamedQuery("GetSequence").UniqueResult<System.Int64>();
回答by trainer
This also does the trick.
这也能解决问题。
<your session variable>.CreateSQLQuery("select <your sequence>.NEXTVAL from dual").UniqueResult<Int64>();
回答by Rox
With NH4 I use this DB agnostic ISession extension method (obviously DB must support sequences)
在 NH4 中，我使用这种与 DB 无关的 ISession 扩展方法（显然 DB 必须支持序列）
public static T GetSequenceNextValue<T>(this ISession session, string sequenceName) where T : struct
{
var dialect = session.GetSessionImplementation().Factory.Dialect;
var sqlQuery = dialect.GetSequenceNextValString(sequenceName);
return session.CreateSQLQuery(sqlQuery).UniqueResult<T>();
}
回答by Gopal
There is a small correction in the mapping given by @Petr Kozelek
@Petr Kozelek 给出的映射中有一个小的更正
<sql-query name="GetSequence" read-only="true">
<return-scalar column="NextNo" type="Int64"/>
<![CDATA[
SELECT SeqName.NEXTVAL as NextNo from DUAL
]]>
</sql-query>
