SQL连接显示空值

Question

我有2个sql表mtblSite_Lavel_Budget和mtblExpenditure_Site_Lavel。 我想加入他们，因此我在下面编写了查询，但是尽管该字段中有值，但一栏总是给出空结果。

查询如下

select mtblExpenditure_Site_Lavel.SFTI_Id, 
mtblExpenditure_Site_Lavel.Site_Lavel_Interventions, 
mtblExpenditure_Site_Lavel.Sub_Site_Lavel_Interventions,
mtblExpenditure_Site_Lavel.Bill_No, mtblExpenditure_Site_Lavel.Date_Of_Bill,
mtblExpenditure_Site_Lavel.Eligible_Exp,
mtblExpenditure_Site_Lavel.Non_Eligible_Exp,
mtblExpenditure_Site_Lavel.Total,
mtblExpenditure_Site_Lavel.Physical_Progress,
mtblSite_Lavel_Budget.Sanction_Amount_DPR  
from mtblExpenditure_Site_Lavel 
left join mtblSite_Lavel_Budget 
   on mtblExpenditure_Site_Lavel.Sub_Site_Lavel_Interventions= mtblSite_Lavel_Budget.Sub_Site_Lavel_Interventions 
WHERE mtblExpenditure_Site_Lavel.SFTI_Id =13 
ORDER BY Date_Of_Bill desc

结果如下

请就此问题提出建议。

Answer 1

尝试这个

   from mtblExpenditure_Site_Lavel left join  mtblSite_Lavel_Budget on 
       mtblExpenditure_Site_Lavel.sfti_id = mtblSite_Lavel_Budget.sfti_id 

我认为它很困惑，因为您正在加入一个字符串列，因此最好总是在可能的地方加入id。