C# 如何在 linq to sql 中编写不等于运算符？
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How to write not equal operator in linq to sql?
提问by Anas Salem
using (RapidWorkflowDataContext context = new RapidWorkflowDataContext())
{
var query = from w in context.WorkflowInstances
from c in context.Workflows
where EmpWorkflowIDs.Contains((int)w.ID) && w.CurrentStateID != c.LastStateID
select w;
return query.ToList();
}
I have 2 tables: Workflows and WorkflowInstances.
我有 2 个表：工作流和工作流实例。
Workflows to store objects and workflowInstances to store instances.
用于存储对象的工作流和用于存储实例的工作流实例。
Workflows Table: ID,Name,FirstStateID,LastStateID
工作流表：ID、名称、FirstStateID、LastStateID
WorkflowInstances Table: ID,Name,WorkflowID,CurrentStateID
工作流实例表：ID、名称、工作流ID、当前状态ID
How to write a query in linq to sql to select the instances from WorkflowInstances which CurrentStateID not equal LastStateID
如何在 linq to sql 中编写查询以从 WorkflowInstances 中选择 CurrentStateID 不等于 LastStateID 的实例
采纳答案by Adel Khayata
You need to revise the join to be on the related columns between the 2 tables, then you add your condition in the where clause, like the following:
您需要将连接修改为 2 个表之间的相关列，然后在 where 子句中添加您的条件，如下所示：
using (RapidWorkflowDataContext context = new RapidWorkflowDataContext())
{
var query = from w in context.WorkflowInstances
join c in context.Workflows on w.WorkflowID equals c.ID
where EmpWorkflowIDs.Contains((int)w.ID)
&& w.CurrentStateID != c.LastStateID
select w;
return query.ToList();
}
回答by Anatolii Gabuza
You can eliminate joinand it should be something like:
你可以消除join，它应该是这样的：
var query = from w in context.WorkflowInstances
where !context.Workflows.Any(c => w.CurrentStateID != c.LastStateID) && EmpWorkflowIDs.Contains((int)w.ID)
select w;
回答by renakre
If you are using lambda expressions, then not(!)goes there:
如果您使用的是 lambda 表达式，则not(!)转到那里：
.Where(p => !p.Whatever...)
