We Keep Coding

Convert Datetime string to date in SQL Server

I have a datetime data from C# like this
2019-03-20T11:25:32.0342949
I tried to convert it to datetime using cast and it triggers error
select cast('2019-03-20T11:25:32.0342949' as date)
Conversion failed when converting date and/or time from character string.
I guess its because of the T in the string.
I tried format also which of course doesn't work because its not identify it as date.
So how can I convert it properly to date. Without some substring methods to extract the date part.

You have to use DATETIME2 instead of DATETIME:
SELECT CAST('2019-03-20T11:25:32.0342949' AS DATETIME2) -- 2019-03-20 11:25:32.0342949
demo on dbfiddle.uk
The issue is the precision of the milliseconds part of your string value. You are using seven digits on the milliseconds part which is not possible on DATETIME. So you can do two things:
shorten the milliseconds part to three digits and use DATETIME
use DATETIME2 for more precision
Use the time, date, datetime2 and datetimeoffset data types for new work. These types align with the SQL Standard. They are more portable. time, datetime2 and datetimeoffset provide more seconds precision. datetimeoffset provides time zone support for globally deployed applications.
source: https://learn.microsoft.com/en-us/sql/t-sql/data-types/datetime-transact-sql
There is also a comparison between DATETIME and DATETIME2 on StackOverflow:
DateTime2 vs DateTime in SQL Server

If you need only date this will work
select cast('2019-03-20T11:25:32.0342949' as date) As DATE
If you need date and time this will work
select cast('2019-03-20T11:25:32.0342949' as datetime2) As DATE
Tried in Sql 15 Its working

You have to take advantage of the CONVERT() method. For example, SELECT CONVERT(date, getdate()), with date being the string you just mentioned. In your case, your datetime string takes up 10 letters of string, so you could also do SELECT CONVERT(VARCHAR(10), GETDATE(), 103). The 3rd parameter is the datetime style you want to convert to.

You should not pass datetime as string from C#, this is the correct way to pass:
string sql = "SELECT * FROM table WHERE datevalue= #date";
SqlParameter dateParam = new SqlParameter("#date", SqlDbType.DateTime);
dateParam .Value = dateValue;
SqlCommand command = new SqlCommand(sql);
command.Parameters.AddWithValue("#date", dateParam );
// then execute the command...

How do I get YYYY-M-d hh:mm:ss as a datetime datatype?

Currently I'm getting error due to datetime format and I want in this way YYYY-M-d hh:mm:ss as a datetime format for datetime datatype but I don't know how to get that. Can You please tell me how to do that? I had a service and client developed in c#.net and both are connected with the database ms sql server and datetime is updated at runtime with current datetime.
Thanks in advance.

Use DateTime.ParseExact
var date = DateTime.ParseExact(dateTimeString,"YYYY-M-d HH:mm:ss", CultureInfo.InvariantCulture);

As you have mentioned MS Sql Server you can get current time in YYYY-MM-DD HH:MI:SS(24h) format as:
SELECT CONVERT(VARCHAR(19), GETDATE(), 120)

Here is a list of all the datetime formats in SQL Server
As for your query the below query should work
SELECT CONVERT(datetime, GETDATE(), 120)

Func<DateTime, string> GetTimeFormated = time => time.ToString("MM/dd/yyyy HH:mm").Split(' ').ToArray().LastOrDefault();

How to use DateTime with SQL queries?

How should I be using c# datetime values in my C# queries?
Up until now I've been doing the following:
Datetime my_time = new DateTime(2012, 09, 05);
cmd.Parameters.AddWithValue("#date", my_time);
cmd.CommandText = "SELECT * FROM sales WHERE date = #date";
Which has been working fine until this morning when I've been getting null errors when retrieving values from the results set.
I changed my date parameter to grab the short date string from my datetime value like this:
cmd.Parameters.AddWithValue("#date", my_time.ToShortDateString());
And it appears to be working fine again.
What is the correct way of doing this? Obviously I'm converting my datetime value to a string, only (presumably) for the database to convert it back to a datetime before evaluating my equality where clause, which seems a little pointless.
Edit:
I'm using SQL Server Compact Edition and the date field in my example has a precision setting of 8 (date, excluding time right?). Does that mean I was passing the full date with 00:00:00.000 on the end before? How might I pass a datetime value to the database without including the time, without converting to a string first?

You can just try with my_time.Date
cmd.Parameters.AddWithValue("#date", my_time.Date);

Do not pass it as a string or will run in troubles with culture formatting.
Try using SqlDateTime instead.

You're not converting the date to a string - AddWithValue knows it is a date, but it is a datetime, so it has a time component. Do your sales have a time component to them?
SELECT * FROM sales WHERE DateDiff(d, #date, date) = 0

Insert into database date with another format

I have a gridview and sqldatasource.
I'm trying to insert new records in database and the Date column type is Date and default format is US , mm/dd/yyyy and I'm trying to insert a date with another format.
SqlDataSource2.InsertCommand = "Insert into test (Name,Date) VALUES (#Name,#CONVERT(Date,'#Date',104))";
SqlDataSource2.InsertParameters.Add("Name", nameText);
SqlDataSource2.InsertParameters.Add("Date", DbType.DateTime, date.Text);
I get: String was not recognized as a valid DateTime.
Thanks

The Date type in format agnostic in the database (unless you store it as a string).
You may first try to get a valid System.DateTime object using DateTime.ParseExact or DateTime.Parse.
Then, set the SqlParameter with this value.
DateTime dateValue = DateTime.Parse(date.Text); // try to make this working first.
SqlDataSource2.InsertCommand= "Insert into test (Name,Date) VALUES (#Name,#Date)";
SqlDataSource2.InsertParameters.Add("Name", nameText);
SqlDataSource2.InsertParameters.Add("Date", DbType.DateTime, dateValue);

First you should use DateTime object instead of Date.Text, First convert your text into DateTime
Second you don't need to format date time while inserting if the data type is datatime at SQLServer table just use.
"Insert into test (Name,Date) VALUES (#Name, #Date)";
You should format date time while retrieving data in select

C#+linq - Inserting DateTime value to the Db in the right format

I have a Db server with DateTime fields in the format of "yyyy-MM-dd mm:hh:ss"
I'm trying to use linq2sql to insert a DateTime member to a DateTime field in one of my tables.
When I do it in SQL I convert the DateTime as following:
"Insert into .... Convert(datetime, getdate(), 120) ..."
But when I try to submit the object from Linq the date time inserts in the wrong format.
Is there a way to define the format that will be inserted to the Db in Linq?
Or is it a DateTime object Issue?

You shouldn't be dealing with a string format when you pass dates and times to the database, any more than you would if you were passing a number. The database should be handling all this for you without any conversions. This is true whether you're using LINQ or within the SQL - almost any time you have to manually do string conversions between types at the database level, you should look for a better solution.
If you read the value back out of the database (as a DateTime again) does it have the right value? If not, in what way is it wrong?