C# 为什么SQL连接意外关闭

在下面的代码中，为什么我的连接关闭了？底部的代码正常工作，因此我的应用程序正常运行。我真的很好奇为什么上面的代码不起作用

using (var dbConn = new SqlConnection(_connectionStrings.SqlServer))
{
    var mySqlText = @"
                       ....  some SQL code here
                     ";

    widgets.ForEach(async widget =>
            {
                await dbConn.ExecuteAsync(mySqlText, widget);   <=== Connection is closed here 
            });
}

它应该有用

using (var dbConn = new SqlConnection(_connectionStrings.SqlServer))
{
    var mySqlText = @"
                       ....  some SQL code here
                     ";

    foreach(var widget in widgets)
    {
        await dbConn.ExecuteAsync(mySqlText, widget); 
    }
}

或

充分解释

---

问题是您正在使用相同的连接并行执行：

using (var dbConn = new SqlConnection(_connectionStrings.SqlServer))
{
    var mySqlText = @"
                       ....  some SQL code here
                     ";

    widgets.ForEach(async widget =>
            {
                await dbConn.ExecuteAsync(mySqlText, widget);   <=== Connection is closed here 
            });
}

使用（var dbConn=newsqlconnection（_connectionStrings.SqlServer））
{
var mySqlText=@”
…这里有一些SQL代码
";
ForEach（异步小部件=>
{
等待dbConn.ExecuteAsync（mySqlText，widget）；是的，
SqlConnection
不是线程安全的；每个线程都应该有自己的连接+1
 using (var dbConn = new SqlConnection(_connectionStrings.SqlServer))
{
    var mySqlText = @"
                       ....  some SQL code here
                     ";
    var allTasks = widgets.Select(widget => dbConn.ExecuteAsync(mySqlText, widget));

    await Task.WhenAll(allTasks);
}

using (var dbConn = new SqlConnection(_connectionStrings.SqlServer))
{
    var mySqlText = @"
                       ....  some SQL code here
                     ";

    widgets.ForEach(async widget =>
            {
                await dbConn.ExecuteAsync(mySqlText, widget);   <=== Connection is closed here 
            });
}