连接到 sql、asp.net c# 的 javascript 出错

Question

我有 javascript 计时器倒计时，代码如下：

<script language="JavaScript">
TargetDate = "<% = TargetDate %>";
/*this is a property in code behind*/BackColor = "palegreen";
ForeColor = "navy";
CountActive = true;
CountStepper = -1;
LeadingZero = true;
DisplayFormat = "%%D%% Days, %%H%% Hours, %%M%% Minutes, %%S%% Seconds.";
FinishMessage = "the auction end"
</script>
<script language="JavaScript" src="countdown.js"></script>
</script>

后面的代码：

public string TargetDate ()
{

    DataTable dataTable = new DataTable(); 
    using (SqlConnection connection = new SqlConnection("Server=localhost;Database=Timer;Trusted_Connectopn=True"))
    using (SqlCommand command = connection.CreateCommand())
    { 
        command.CommandText = "select * from endTime"; 
        connection.Open(); 
        SqlDataReader reader = command.ExecuteReader(); 
        dataTable.Load(reader); }
}

我收到错误： “t.TargetDate()”：并非所有代码路径都会返回值。

当我尝试写 return 时，我遇到了另一个错误...这意味着我不知道该怎么做:)

Answer 1

首先，您必须根据函数规范以字符串形式返回目标日期值。
您应该读取数据表并将其返回。像这样的东西

public string TargetDate ()
{
    String tDate = "";
    DataTable dataTable = new DataTable(); 
    using (SqlConnection connection = new SqlConnection("Server=localhost;Database=Timer;Trusted_Connection=True"))
    using (SqlCommand command = connection.CreateCommand())
    { 
        command.CommandText = "select * from endTime"; 
        connection.Open(); 
        SqlDataReader reader = command.ExecuteReader(); 
        dataTable.Load(reader);
         tDate = dataTable.Rows[0][0].toString(); // Expecting the first row and first column
 }
return tDate;
}

希望这有帮助。

Answer 2

你的方法应该返回字符串。事实并非如此。

public string TargetDate

没有返回。

使用ExecuteScalar，而不是ExecuteReader。

返回字符串值。

Answer 3

您的连接字符串中还存在拼写错误：Trusted_Connectopn 应为 Trusted_Connection