executiontenonquery连接属性尚未初始化。在asp.net中 [英] executenonquery connection property has not been initialized. in asp.net

问题描述

代码 -

 SqlConnection con =  new  SqlConnection（ConfigurationManager。 ConnectionStrings [  constr]。ConnectionString）; 
 con.Open（）; 
 
 SqlCommand cmd =  new  SqlCommand（  INSERT INTO Employee（Dept_Name，Dept_ID，Emp_Name）SELECT Dept_ID，Dept_Name FROM Department WHERE Dept_Name = ddlDeptName.SelectedValue）; 
 cmd.Parameters.AddWithValue（  Emp_Name，txtName.Text.Trim（）） ; 
 cmd.Parameters.AddWithValue（  Dept_Name，ddlDeptName.SelectedValue）; 
 cmd.ExecuteNonQuery（）; 
 con.Close（）; 

连接字符串 -

 <   connectionstrings  >  
 <   add  < span class =code-attribute>   name   =  constr >  
 connectionString =Data Source =（LocalDB）\ v11.0; AttachDbFilename = c：\\ \\users\rohit kumar \documents\visual studio 2013 \Projects\Data Grid1 \Data Grid1\App_Data\Employee.mdf; Integrated Security = True
 providerName =System.Data。的SqlClient/&安培; GT; 
 <   / add  >  <   / connectionstrings  >  

解决方案

您尚未设置命令的连接。将以下行添加到您的代码中

 cmd.Connection = con; 

或者在创建时定义连接命令

 SqlCommand cmd =  new  SqlCommand（  INSERT INTO Employee（Dept_Name，Dept_ID，Emp_Name）SELECT Dept_ID，Dept_Name FROM Department WHERE Dept_Name = ddlDeptName.SelectedValue，con）; 

作为旁注，命令看起来不正确。如果需要使用下拉列表中的值，则需要将它们定义为参数。



另一方面，Dept_Name，Dept_ID的值来自SELECT语句，因此不需要那些作为参数。



您似乎也与列数不匹配。 Insert定义了3列但select只提供了2

你需要指定在sql命令中使用哪个连接。

 SqlCommand cmd =  new  SqlCommand（  INSERT INTO Employee（Dept_Name， Dept_ID，Emp_Name）SELECT Dept_ID，Dept_Name FROM Department WHERE Dept_Name = ddlDeptName.SelectedValue，con）; 

并且您还没有在您的参数中包含参数sql语句，它应该如下所示

  INSERT   INTO 员工（Dept_ID，Dept_Name） SELECT  Dept_ID，Dept_Name  FROM 部门 WHERE  Dept_Name =  @ Dept_Name  

因为你有一个参数，你可以设置如下

 cmd.Parameters.AddWithValue（  @ Dept_Name，ddlDeptName.SelectedValue）; 

Code-

SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["constr"].ConnectionString);
con.Open();
      
SqlCommand cmd= new SqlCommand("INSERT INTO Employee (Dept_Name, Dept_ID, Emp_Name) SELECT Dept_ID, Dept_Name FROM Department WHERE Dept_Name = ddlDeptName.SelectedValue ");
cmd.Parameters.AddWithValue("Emp_Name", txtName.Text.Trim());
cmd.Parameters.AddWithValue("Dept_Name", ddlDeptName.SelectedValue);
cmd.ExecuteNonQuery();
con.Close();

Connection String-

<connectionstrings>
  <add name="constr">
       connectionString="Data Source=(LocalDB)\v11.0;AttachDbFilename=c:\users\rohit kumar\documents\visual studio 2013\Projects\Data Grid1\Data Grid1\App_Data\Employee.mdf;Integrated Security=True" 
       providerName="System.Data.SqlClient"/&gt;
</add></connectionstrings>

解决方案

You haven't set the connection for the command. Add the following line to your code

cmd.Connection = con;

Or define the connection when creating the command

SqlCommand cmd= new SqlCommand("INSERT INTO Employee (Dept_Name, Dept_ID, Emp_Name) SELECT Dept_ID, Dept_Name FROM Department WHERE Dept_Name = ddlDeptName.SelectedValue ", con);

As a side note the command doesn't look right. If you need to use values from a drop down list, you need to define them as parameters.

On the other hand, the values for Dept_Name, Dept_ID come from the SELECT statement so those aren't needed as parameters.

It also seems that you have a mismatch with column count. Insert defines 3 columns but the select provide only 2

you need to specify which connection to use in sql command.

SqlCommand cmd= new SqlCommand("INSERT INTO Employee (Dept_Name, Dept_ID, Emp_Name) SELECT Dept_ID, Dept_Name FROM Department WHERE Dept_Name = ddlDeptName.SelectedValue ", con);

and also you haven't include parameters in your sql statement, it should be like below

INSERT INTO Employee (Dept_ID,Dept_Name) SELECT Dept_ID, Dept_Name FROM Department WHERE Dept_Name = @Dept_Name  

since you have one parameter, you can set it as below

cmd.Parameters.AddWithValue("@Dept_Name", ddlDeptName.SelectedValue);

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