C＃中的SELECT語句如果爲空（Visual Studio）

Select語句僅返回非空的技術名稱。由於技術人員尚未被分配到打開門票，我需要這個返回所有產品代碼，不管技術名稱是否填寫或爲空。C＃中的SELECT語句如果爲空（Visual Studio）

string selectStatement = 
      "SELECT ProductCode, DateOpened, Customers.Name AS CustName, " + 
      "Technicians.Name as TechName, Title, DateClosed " + 
      "FROM Incidents " + 
      "JOIN Customers ON Incidents.CustomerID = Customers.CustomerID " + 
      "JOIN Technicians ON Incidents.TechID = Technicians.TechID " + 
      "WHERE DateClosed IS NULL " + 
      "ORDER BY DateOpened";

來源

2017-01-31 javanewb2.0

[加入的可視化表示]（https://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins） –

如果您使用'JOIN'，實際上使用'INNER JOIN' –

改變此密碼

"JOIN Technicians ON Incidents.TechID = Technicians.TechID " +

這個

"LEFT JOIN Technicians ON Incidents.TechID = Technicians.TechID " +

來源

2017-01-31 09:13:34

您可以使用內部聯接象下面這樣：

"inner join Technicians ON Incidents.TechID = Technicians.TechID "

最終查詢

string selectStatement = 
     "SELECT ProductCode, DateOpened, Customers.Name AS CustName, " + 
     "Technicians.Name as TechName, Title, DateClosed " + 
     "FROM Incidents " + 
     "inner JOIN Customers ON Incidents.CustomerID = Customers.CustomerID " + 
     "inner JOIN Technicians ON Incidents.TechID = Technicians.TechID " + 
     "WHERE DateClosed IS NULL " + 
     "ORDER BY DateOpened";

來源

2017-01-31 09:22:33 Saif

C＃中的SELECT語句如果爲空（Visual Studio）

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