Date and Time Formatting in VB.net and SQL Server

问题

I have a table in which data is been logged in 'yy/MM/dd HH:mm:ss' format and my regional setting is '2016-04-02 14:25:15' type. I want to get details in a following query but it is not populating any results

The query I used is

select 
    Date_time, alarm_id, alarm_message 
from 
    table01 
where 
    Date_time between '" & DateTimePicker5.Value & "' and '" & DateTimePicker6.Value & "'

I also tried using one function which I had written is

Private Function FormatDate(ByVal dat As String) As String
    Dim FTDate As Date
    FTDate = FormatDateTime(Convert.ToDateTime(dat), DateFormat.ShortDate)
    FormatDate = Format(FTDate, "yy/MM/dd HH:mm:ss")
End Function

And used the same again in query as

select 
    Date_time, alarm_id, alarm_message  
from 
    table01 
where 
    Date_time between '" & formatdate(DateTimePicker5.Value) & "' and '" & formatdate(DateTimePicker6.Value) & "'

Please suggest appropriate answer make sure that I don't want to change my regional setting and on form load event. I've written the following code

      DateTimePicker5.Format = DateTimePickerFormat.Custom
      DateTimePicker5.CustomFormat = "yy/MM/dd HH:mm:ss"
      DateTimePicker6.Format = DateTimePickerFormat.Custom
      DateTimePicker6.CustomFormat = "yy/MM/dd HH:mm:ss"

The Table Is In Below Mentioned Format

  **Datetime        V1   P1**
16/08/29 19:12:24   10  STB-1
16/08/29 19:12:19   20  STB-1 
16/08/29 19:12:18   30  STB-1 
16/08/29 19:09:50   40  STB-1

回答1:

This is some what a tricky solution. Since year kept as 'yy' in the backend,following are the assumptions.

if the year part of the database field is between 00 to 16 ,need to consider this as 2000 to 2016. for the remaining values script will consider year as 1917 to 1999 .

Can you try with the below script.

SELECT Date_time, alarm_id, alarm_message 
FROM table01 
WHERE 
       CASE WHEN LEFT(Date_time,2) between 00 and RIGHT(year(getdate()),2) THEN CONVERT(DATETIME,'20'+Date_time)
        ELSE CONVERT(DATETIME,'19'+Date_time) END between '" & DateTimePicker5.Value & "' and '" & DateTimePicker6.Value & "'

回答2:

Never ever ever EVER use string concatenation to put values into a query like that! It's practically begging to wake up one morning and find out your site was hacked six months ago.

The first thing you need to do is fix the schema, so that your date values are actually stored as DateTime columns. There are so many reasons for this, I can't even begin to describe them all. Just do it!

Once that's done, you build the query like this:

Const SQL As String = _
   "SELECT  Date_time, alarm_id, alarm_message " &
   " FROM table01" &
   " WHERE Date_time between @StartTime AND @EndTime"

Hey, look: it's a constant. That's not strictly necessary. I usually just use a normal Dim'd String value. I wanted to prove a point here: you SQL statement is set to use specific place holders that will never at any point have data put in them. The values you provide for those @StartTime and @EndTime values will be completely separted and quarantined from your SQL command, such that no possibility for injection ever exists.

Once you have your SQL command string, you can use it like this (repeating the string definition so everything is in one place):

Const SQL As String = _
   "SELECT  Date_time, alarm_id, alarm_message " &
   " FROM table01" &
   " WHERE Date_time between @StartTime AND @EndTime" 
Using cn As New SqlConnection("connection string here"), _
      cmd As New SqlCommand(SQL, cn)

    cmd.Parameters.Add("@StartTime", SqlDbType.DateTime).Value = DateTimePicker5.Value
    cmd.Parameters.Add("@EndTime", SqlDbType.DateTime).Value = DateTimePicker6.Value

    cn.Open()
    Using rdr As SqlDataReader = cmd.ExecuteReader()
        While rdr.Read()

        End While
    End Using
End Using

Or if you're filling a DataTable:

Dim result As New DataTable
Const SQL As String = _
   "SELECT  Date_time, alarm_id, alarm_message " &
   " FROM table01" &
   " WHERE Date_time between @StartTime AND @EndTime" 
Using cn As New SqlConnection("connection string here"), _
      cmd As New SqlCommand(SQL, cn), _
      ad As New SqlDataAdapter(cmd)

    cmd.Parameters.Add("@StartTime", SqlDbType.DateTime).Value = DateTimePicker5.Value
    cmd.Parameters.Add("@EndTime", SqlDbType.DateTime).Value = DateTimePicker6.Value

    ad.Fill(result)
End Using

Note that using this method, you never have to worry about your DateTime format. ADO.Net figures it out for you. It knows about .Net DateTime objects, and it knows about Sql Server DateTime columns, and it handles conversions between the two types naturally.

回答3:

You can use Convert function.

select 
    Date_time, alarm_id, alarm_message 
from 
    table01 
where 
    Convert(Datetime,Date_time) between Convert(Datetime,'" & DateTimePicker5.Value & "') and Convert(Datetime,'" & DateTimePicker6.Value & "')

回答4:

Since:

Console.WriteLine(#1/31/2016 10:23:22 AM#.ToString("yy/MM/dd HH:mm:ss"))

returns 16/01/31 10:23:22

I guess that:

select 
  Date_time, alarm_id, alarm_message 
from 
  table01 
where 
  (Date_time >= '" & DateTimePicker5.Value.ToString("yy/MM/dd HH:mm:ss") & "' ) 
  and (Date_time < '" & DateTimePicker6.Value.ToString("yy/MM/dd HH:mm:ss") & "')

will do the trick.

Notice that I've changed the between with simple compare conditions

Run this in SQL Server and check the results:

create table #dateTest (
    testDate datetime
)

insert into #dateTest values ('2016-03-01')
select * from #dateTest


declare @fromDate datetime
set @fromDate = '2016-01-01'

declare @toDate datetime
set @toDate = '2016-03-01'


select 
    testDate 
from 
    #dateTest
where
    ( testDate between @fromDate and @toDate ) 
    -- 2016-03-01 00:00:00.000


select 
    testDate 
from 
    #dateTest
where
    ( testDate <= @fromDate )
    and ( testDate < @toDate )
    -- No rows selected


drop table #dateTest

来源：https://stackoverflow.com/questions/39284596/date-and-time-formatting-in-vb-net-and-sql-server

标签

sql

sql-server

vb.net

datetime

datetime-format