C# 比较asp.net中表中的值

我正在编辑代码隐藏文件，在数据库中，我将这4个表链接在一起：

Table :Compannies
--------------------
companyId
--------------------
companyName
--------------------

以及：

以及：

以及：

现在，我想检查所有companyName，如果选择相应地=“YES”，则执行该操作

string sqlIns = "SELECT companyName FROM Companies WHERE companyId IN
                  (SELECT companyId FROM UserCompany WHERE userId IN 
                   (SELECT UserId FROM Users WHERE Email IN 
                    (SELECT Email FROM Choice WHERE Choice='YES')"

SqlConnection conn = new SqlConnection(ConfigurationSettings.AppSettings["connectionString"]);
                    conn.Open();
try
{
    SqlCommand cmdIns = new SqlCommand(sqlIns, conn);    
    if (cmdIns.Parameters.compareValue("currentCompanyName", companyName))//how to compare?
    {
         //action here
    }
    else
    {
         //another action
    }

    cmdIns.ExecuteNonQuery();

    cmdIns.Parameters.Clear();
    cmdIns.Dispose();
    cmdIns = null;
}
catch (Exception ex)
{
      throw new Exception(ex.ToString(), ex);
}
finally
{
      conn.Close();
}

---

我不知道如何比较从表中提取的值，我的代码中是否存在语法或逻辑错误？

尝试使用

内部联接

而不是嵌套查询：

以下是更改的查询：

SELECT cn.companyName from companies cn 
INNER JOIN UserCompany uc ON uc.companyid = cn.companyid 
INNER JOIN Users u ON u.userId = uc.userId
INNER JOIN Choice c ON c.Email = u.Email And c.Choice = @Choice
WHERE cn.CompanyName = @CompanyName;

示例代码如下所示：

string commandText = @"SELECT cn.companyId, cn.companyName from companies cn 
                       INNER JOIN UserCompany uc ON uc.companyid = cn.companyid 
                       INNER JOIN Users u ON u.userId = uc.userId
                       INNER JOIN Choice c ON c.Email = u.Email And c.Choice = @Choice
                       WHERE cn.CompanyName = @CompanyName;";

string connectionString = ConfigurationSettings.AppSettings["connectionString"];

using (SqlConnection connection = new SqlConnection(connectionString))
{
    SqlCommand command = new SqlCommand(commandText, connection);        

    command.Parameters.AddWithValue("@Choice", "YES");
    command.Parameters.AddWithValue("@CompanyName", "currentCompanyName");

    try
    {
        connection.Open();            

        datagridview.DataSource = command.ExecuteReader();
        datagridview.DataBind();

    }
    catch (Exception ex)
    {
       //handle exception
    }
}

---

但是在

SqlCommand

中没有定义参数？什么是cmdIns.Parameters.compareValue（）方法？我认为它不存在。你的问题不清楚。似乎你想将结果与另一个公司名称进行比较？是的，它是正确的！我只想获取“choice”=“YES”的公司名称Hi Zeeshan，“cmdIns.Parameters.compareValue（）”可能不存在，我只是不知道如何设置条件。如何使用该内部关节来获取choice=YES的所有公司ID？您可以在查询中同时使用

选择cn.companyId、cn.companyName

或其中任何一个。在上面的代码中，我的意思是，我应该将cn.CompanyName=@CompanyName的位置改为c.Choice='YES'吗？它没有正确返回。不，您不必在查询中进行更改。对于前面带有

@

符号的变量，您将在参数中提供值。请参见

command.Parameters.AddWithValue

这里您给@Parameters赋值。对不起，我弄糊涂了。所以在SqlCommand命令之后=新的SqlCommand（commandText，connection）；和command.Parameters.AddWithValue（“@Choice”，“YES”）；我能得到什么。看起来它将为表选项添加值YES。但这里我需要的是获取companyID where Choice=“YES”，然后在我的另一个问题中，我将从数据网格中删除带有该companyID的行。

string sqlIns = "SELECT companyName FROM Companies WHERE companyId IN
                  (SELECT companyId FROM UserCompany WHERE userId IN 
                   (SELECT UserId FROM Users WHERE Email IN 
                    (SELECT Email FROM Choice WHERE Choice='YES')"

SqlConnection conn = new SqlConnection(ConfigurationSettings.AppSettings["connectionString"]);
                    conn.Open();
try
{
    SqlCommand cmdIns = new SqlCommand(sqlIns, conn);    
    if (cmdIns.Parameters.compareValue("currentCompanyName", companyName))//how to compare?
    {
         //action here
    }
    else
    {
         //another action
    }

    cmdIns.ExecuteNonQuery();

    cmdIns.Parameters.Clear();
    cmdIns.Dispose();
    cmdIns = null;
}
catch (Exception ex)
{
      throw new Exception(ex.ToString(), ex);
}
finally
{
      conn.Close();
}

SELECT cn.companyName from companies cn 
INNER JOIN UserCompany uc ON uc.companyid = cn.companyid 
INNER JOIN Users u ON u.userId = uc.userId
INNER JOIN Choice c ON c.Email = u.Email And c.Choice = @Choice
WHERE cn.CompanyName = @CompanyName;

string commandText = @"SELECT cn.companyId, cn.companyName from companies cn 
                       INNER JOIN UserCompany uc ON uc.companyid = cn.companyid 
                       INNER JOIN Users u ON u.userId = uc.userId
                       INNER JOIN Choice c ON c.Email = u.Email And c.Choice = @Choice
                       WHERE cn.CompanyName = @CompanyName;";

string connectionString = ConfigurationSettings.AppSettings["connectionString"];

using (SqlConnection connection = new SqlConnection(connectionString))
{
    SqlCommand command = new SqlCommand(commandText, connection);        

    command.Parameters.AddWithValue("@Choice", "YES");
    command.Parameters.AddWithValue("@CompanyName", "currentCompanyName");

    try
    {
        connection.Open();            

        datagridview.DataSource = command.ExecuteReader();
        datagridview.DataBind();

    }
    catch (Exception ex)
    {
       //handle exception
    }
}