Date and Time Formatting in VB.net and SQL Server - sql

Question

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

Answer 1

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

Answer 2

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 & "'

Answer 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 & "')

Answer 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