如何将C＃now与SQL Server datetime进行比较

Question

你如何将C＃现在与SQL Server日期时间进行比较？

我尝试了十件事，但没有任何作用：

string sql;
DataTableReader dr;
sql = "Select StartDate from mytable";

SqlDataAdapter da = new SqlDataAdapter(sql, ConfigurationManager.AppSettings["DB"]);
DataTable dt = new DataTable();
da.Fill(dt);

dr = dt.CreateDataReader();

var now = DateTime.Now.Date;

while (dr.Read())
{
    // StartDate datatype is a SQL Server datetime and possibly can be null
    if(dr["StartDate"] < now) 
    {
        // code for start date is in the past
    }
}

Answer 1

您必须将SQL Server字符串转换为datetime。

// StartDate datatype is a SQL Server datetime and possibly can be null
if(Convert.ToDateTime(dr["StartDate"]) < now) 
{
    // code for start date is in the past
}