更新與Linq中選擇查詢值到SQL

Question

Update TableToBeUpdated 
Set ColumnNameId = (Select MasterColumnId 
        from MasterTable where Id = @Id) 
Where ForeingKeyId = @Id 
    AND AnotherColumn = @AnotherColumn 

如何與一個select語句和使用子查詢的更新語句實現上述的？

目前我在想什麼。

//First Select statement 
    var tableTBU = (from t in MsDataContext.TableToBeUpdated 
      where t.ForeingKeyId == <valueFromVariable> 
      select t).SingleOrDefault(); 

    //Second select statement 
    var masterIdValue = (from m in MsDataContext.MasterTable 
       where m.Id == <valueFromVariable> 
       select mod.MasterColumnId).SingleOrDefault(); 


    tableTBU.ColumnNameId = masterIdValue ; 
    tableTBU.SomeOtherColumn = "dkjsdlfs"; 
    //Some more things to be updated. 

    //UpdateStatement 
    MsDataContext.SubmitChanges(); 

Answer 1

LINQ到SQL效果最好，如果你讓LINQ引擎來管理密鑰（我假定MasterTable和TableToBeUpdated之間的關係是一個一對一）：

using (DataContext dc = new DataContext()) 
{ 
    var objectToUpdate = dc.MasterTable.Single(a => a.Id == id).TableToBeUpdated; 

    objectToUpdate.SomeOtherColumn = "dkjsdlfs"; 
    dc.SubmitChanges(); 
} 

這也假定您已經關聯了兩個表，可以通過設計器使用關聯或通過數據庫中的外鍵關係手動關聯。

UPDATE：

既然你沒有一個現有的外鍵關係，那麼你就需要手動關聯表。根據上面的SQL語句：

using (DataContext dc = new DataContext()) 
{ 
    var objectToUpdate = dc.TableToBeUpdated 
     .Single(b => b.ForeignKeyId.Contains(dc.MasterTable.Single(a => a.Id == id).Id) 
      && b.AnotherColumn == anotherColumn); 

    objectToUpdate.SomeOtherColumn = "dkjsdlfs"; 
    dc.SubmitChanges(); 
}