SQL更新给错误的结果

Question

我在VB.NET

下面的SQL语句

Dim READER As SqlDataReader 

    Try 
     konneksie.Open() 
     Dim Query As String 

     Query = "Update blokkeklaar " & _ 
     " set Klaarvb = 'JA' " & _ 
     " where KlaarEZY = 'YES'" & _ 
     " Update blokkeklaar " & _ 
     " set Klaarvb = 'NEE' " & _ 
     " where KlaarVB IS NULL" 

     COMMAND = New SqlCommand(Query, konneksie) 
     READER = COMMAND.ExecuteReader 
     MessageBox.Show("KlaarVB verander ") 
     konneksie.Close() 
    Catch ex As Exception 
     MessageBox.Show(ex.Message) 
    Finally 
    End Try 
    konneksie.Close() 

我不明白为什么klaarvb填充了“东东”，其中klaarvb不为空？

Answer 1

你正在试图做的2个独立的更新有一个声明。如果你想有一个单独的语句的解决方案，尝试：

update blokkeklaar 
set Klaarvb = case 
       when KlaarEZY = 'YES' then 'JA' 
       when KlaarVB is null then 'NEE' 
       else Klaarvb -- Thanks hurcane 
       end; 

这会按顺序评估，并退出当条件满足，因此，如果第一个条件为真，第二个将不评估或应用。

Answer 2

你必须把语句之间分号或单独执行它们：

Query = "Update blokkeklaar " & _ 
     " set Klaarvb = 'JA' " & _ 
     " where KlaarEZY = 'YES';" & _ //<--put semiColon here 
     " Update blokkeklaar " & _ 
     " set Klaarvb = 'NEE' " & _ 
     " where KlaarVB IS NULL" 

另外，作为一个侧面说明，你最好使用ExecuteNonQuery代替ExecuteReader