选择最小日期值并计算日期值？

Question

I have a table called "SUMMARYDATA" which has columns "STATUSIN,STATUSOUT,LATECOME" and I want to select min value on column "STATUSIN". And make a condition: IF MIN(STATUSIN) > "08.00 AM" Then LATECOME = MIN(STATUSIN) - "08.00 AM" . How to select min date value? And how to calculate MIN(STATUSIN) - "08.00 AM" ?

This is my code to display data from database:

    <asp:Repeater ID="rptrSUMMARYDATA" runat="server">
        <HeaderTemplate>
            <table class="table">
                <thead>
                    <tr>
                        <th>IN</th>
                        <th>OUT</th>
                        <th>LATECOME</th>
                    </tr>
                </thead>
                <tbody>
        </HeaderTemplate>
        <ItemTemplate>
            <tr>
                <td><%# Eval("STATUSIN") %></td>
                <td><%# Eval("STATUSOUT") %></td>
                <td><%# Eval("LATECOME") %></td>
            </tr>
        </ItemTemplate>
        <FooterTemplate>
                </tbody>
            </table>
        </FooterTemplate>
    </asp:Repeater>  

This is my code on backend:

     private void BindSUMMARYDATARptr()
    {
        String CS = ConfigurationManager.ConnectionStrings["MANHOURConnectionString"].ConnectionString;
        using (SqlConnection con = new SqlConnection(CS))
        {
            using (SqlCommand cmd = new SqlCommand("SELECT * FROM SUMMARYDATA", con))
            {
                using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
                {
                    DataTable dtDaily = new DataTable();
                    sda.Fill(dtDaily);

                    rptrSUMMARYDATA.DataSource = dtDaily;
                    rptrSUMMARYDATA.DataBind();
                }

            }

        }
    }

Answer 1

Can you try this..

  SELECT  STATUSIN,STATUSOUT, CASE WHEN CAST(STATUSIN AS TIME) > CAST('08:00:00' AS TIME) 
           THEN CONVERT(varchar, dateadd(s, -28800 ,STATUSIN), 108)  END AS LATECOME 
  FROM SUMMARYDATA

Answer 2

Get the MIN from datatable and use DateTime.Subtract

var minIN = Convert.ToDateTime(dt.AsEnumerable().Min(row => row["IN"]));
Console.WriteLine($"LATECOME {minIN.Subtract(minIN.Date + new TimeSpan(8, 0, 0))}");

Note: AsEnumerable is part of System.Data.DataSetExtensions . Install this package from nuget

To Update directly in Database (I would not recommend this, unless it is absolutely needed)

UPDATE SUMMARYDATA 
  SET LATECOME =  CASE WHEN DATEDIFF(s,DATEADD(HOUR, 8, CAST(CAST((select MIN(STATUSIN) from SUMMARYDATA)  AS DATE) AS DATETIME)),(select MIN(STATUSIN) from SUMMARYDATA)) > 0 THEN
  (CONVERT(TIME,(select MIN(STATUSIN) from SUMMARYDATA)-DATEADD(HOUR, 8, CAST(CAST((select MIN(STATUSIN) from SUMMARYDATA)  AS DATE) AS DATETIME)))) ELSE NULL END

Answer 3

select DATEADD(minute, -iif(CAST(STATUSIN as time) > CAST('08:00' as time), DATEDIFF(MINUTE,CAST('08:00' as time),CAST(STATUSIN as time)) ,0) , STATUSIN) as LATECOME
from SUMMARYDATA

Answer 4

Try this:

select STATUSIN,STATUSOUT,case when CAST(STATUSIN as time) > CAST('08:00' as time) then 
DATEDIFF(MINUTE,CAST('08:00' as time),CAST(STATUSIN as time)) 
end as LATECOME from test;