C＃中的SQL更新语句

  • Z时代
  • 2024-01-10
  • 分类：问答

我有桌子 

   P_ID   LastName  FirstName  Address  City
   1        Hansen    Ola                
   2        Svendson   Tove
   3        Petterson   Kari
   4        Nilsen       Johan
...and so on

如何在C＃中更改编辑代码

 string firstName = "Ola";
 string  lastName ="Hansen";
 string  address = "ABC";
 string city = "Salzburg";
 string connectionString = System.Configuration.ConfigurationManager
                          .ConnectionStrings["LocalDB"].ConnectionString;
 using (SqlConnection connection = new SqlConnection(connectionString))
     using (SqlCommand command = connection.CreateCommand())
 { 
   command.CommandText = "INSERT INTO Student (LastName, FirstName, Address, City) 
                          VALUES (@ln, @fn, @add, @cit)";
   command.Parameters.AddWithValue("@ln", lastName);
   command.Parameters.AddWithValue("@fn", firstName);
   command.Parameters.AddWithValue("@add", address);
   command.Parameters.AddWithValue("@cit", city);
   connection.Open();
   command.ExecuteNonQuery();
   connection.Close();
 }

要编辑条目，其中 字段姓价值和 字段名字值。

我不想这样使用

 UPDATE Persons  SET Address='Nissestien 67', City='Sandnes' 
 WHERE LastName='Tjessem'     AND FirstName='Jakob'

然后我将原始声明编辑为

 command.CommandText = "UPDATE Student(LastName, FirstName, Address, City) 
   VALUES (@ln, @fn, @add, @cit) WHERE LastName='" + lastName + 
                           "' AND FirstName='" +  firstName+"'";

但是该语句未得到执行，为什么会引发SQL异常？有没有解决的办法？

回答：

这不是更新SQL中记录的正确方法：

command.CommandText = "UPDATE Student(LastName, FirstName, Address, City) VALUES (@ln, @fn, @add, @cit) WHERE LastName='" + lastName + "' AND FirstName='" + firstName+"'";

您应该这样写：

command.CommandText = "UPDATE Student 
SET Address = @add, City = @cit Where FirstName = @fn and LastName = @add";

然后，添加与为插入操作添加的参数相同的参数。

以上是 C＃中的SQL更新语句 的全部内容， 来源链接： utcz.com/qa/435108.html

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