C＃SqlDataAdapter必须声明标量变量Sql Exception

问题描述

C＃的新手，并且在Windows窗体应用程序上工作。我试图对sql数据库执行更新查询，但始终遇到“必须声明标量变量”错误，我不明白为什么。

以下代码成功打开了连接。我的更新声明有效。浏览有关该主题的很多文章，但我只是没有看到我的错误...任何帮助将不胜感激。

public void SetJobStatus(long JobId)
{
    string strsql = "update Jobmaster set jobstatus = 5 where equid = @stationId AND ID <> @jobId AND OfflineEntry = 0;";

    using (sqlConnection conn = new sqlConnection())
    {
        conn.ConnectionString = GlobalVars.connString;
        conn.open();
        // use the connection here,and check to confirm it is open
        if (conn.State != ConnectionState.Open)
        {
            if (conn != null)
            {
                conn.Close();
            }
            conn.open();
        }
        sqlCommand command;
        sqlDataAdapter adapter = new sqlDataAdapter();

        command = new sqlCommand(strsql,conn);
        //below AddWithValue gives error:
        //System.Data.sqlClient.sqlException: 'Must declare the scalar variable "@stationId".'
        //command.Parameters.AddWithValue("@stationId",1);
        //command.Parameters.AddWithValue("@jobId",JobId);
        
        //next I tried this,and the same error:
        //System.Data.sqlClient.sqlException: 'Must declare the scalar variable "@stationId".'
        command.Parameters.Add("@stationId",sqlDbType.Int);
        command.Parameters["@stationId"].Value = 1;
        command.Parameters.Add("@jobId",sqlDbType.Int);
        command.Parameters["@jobId"].Value = JobId;

        adapter.UpdateCommand = new sqlCommand(strsql,conn);
        adapter.UpdateCommand.ExecuteNonQuery();
    }
}

解决方法

我已经检查了您的代码，需要进行一些更改。请尝试运行以下代码：

public void SetJobStatus(int JobId)
{
    string strSql = "update Jobmaster set jobstatus = 5 where equid = @stationId AND ID <> @jobId AND OfflineEntry = 0;";

    using (SqlConnection conn = new SqlConnection())
    {
        try
        {
            conn.ConnectionString = GlobalVars.connString;
            conn.Open();
            SqlCommand command = new SqlCommand(strSql,conn);
            command.CommandType = CommandType.Text;
            command.Parameters.Add("@stationId",SqlDbType.Int);
            command.Parameters["@stationId"].Value = 1;
            command.Parameters.Add("@jobId",SqlDbType.Int);
            command.Parameters["@jobId"].Value = JobId;
            command.ExecuteNonQuery();
        }
        catch (Exception ex)
        {
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
            }
        }
        finally
        {
            if (conn.State == ConnectionState.Open)
            {
                conn.Close();
            }
        }
    }
}

提示：

• 在任务完成后或出现错误时始终关闭连接。

,

感谢在这里发消息的每个人。 WSC的评论确实改变了技巧adapter.UpdateCommand = command;。在进行WSC更改后，我尝试了三种添加参数的方法-其中两种有效，一种没有。

我的修订代码如下。我在代码中列出了所有三种变体，希望这对其他人有帮助。

public void SetJobStatus(long JobId)
{
    string strSql = "update Jobmaster set jobstatus = 5 where equid = @stationId AND ID <> @jobId AND OfflineEntry = 0;";

    using (SqlConnection conn = new SqlConnection())
    {
        conn.ConnectionString = GlobalVars.connString;
        conn.Open();
        // use the connection here,and check to confirm it is open
        if (conn.State != ConnectionState.Open)
        {
            if (conn != null)
            {
                conn.Close();
            }
            conn.Open();
        }
        SqlCommand command;
        SqlDataAdapter adapter = new SqlDataAdapter();

        command = new SqlCommand(strSql,conn);
        
        //works
        command.Parameters.AddWithValue("@stationId",GlobalVars.stationId);
        command.Parameters.AddWithValue("@jobId",JobId);

        //works
        //command.Parameters.Add("@stationId",SqlDbType.Int);
        //command.Parameters["@stationId"].Value = 5;
        //command.Parameters.Add("@jobId",SqlDbType.Int);
        //command.Parameters["@jobId"].Value = JobId;

        //throws error at adapter.UpdateCommand.ExecuteNonQuery line:
        //'The parameterized query '(@stationId int,@jobId int)update Jobmaster set jobstatus = 5 wh' expects the parameter '@stationId',which was not supplied.'
        //command.Parameters.Add("@stationId",SqlDbType.Int,5);
        //command.Parameters.Add("@jobId",(int)JobId);

        adapter.UpdateCommand = command;
        adapter.UpdateCommand.ExecuteNonQuery();
    }

}