my question looks simple: in my client/server application I want to record a specific date provided by the client.
The problem is that I don't know the regional settings of the client, and I don't know the regional settings of the SQL Server.
How can the client application provide a date in whatever format (last login of a specific user) and store it in a SQL Server table that might be installed with a different regional settings (french, english, italian, german, etc...).
Simple: don't use strings. Use a parameter that is typed as a datetime; can be as simple as:
DateTime when = ...
using(var cmd = conn.CreateCommand()) {
cmd.CommandText = "... #when ...";
cmd.Parameters.AddWithValue("when", when);
cmd.ExecuteNotQuery();
}
or with "dapper":
conn.Execute("... #when ...", new { when });
Dates/times are actually just numbers. It is only when you write/parse it as a string that formatting is an issue.
Just store everything in UTC date in sqlserver. And while retrieving the date convert the utc date to the timezone of the user. I hope users timezone is maintained in your database.
You will need a timezone table and a conversion function that will convert the UTC time to the users local time.
to insert a date in SQL use a string in the form 'YYYYMMDD'
what comes from the client-side you sould know what is it
You should use Parameters, but you also can format date to ISO format by date.ToString("s")
Use datetime format, and store dates as UTC time.
You'll probably also be interested in datetimeoffset.
Validation part
DateTime dt;
string YourDate = "Your Date";
if (DateTime.TryParse(YourDate, out dt))
{
//Your Code
}
Stored Procedure Record Insertion/Retrieval
using (System.Data.SqlClient.SqlConnection con = new SqlConnection("YourConnection string"))
{
con.Open();
SqlCommand cmd = new SqlCommand();
string expression = "Date Parameter value";
DateTime dt;
if (DateTime.TryParse(expression, out dt))
{
//Your Code
}
cmd.CommandType = CommandType.StoredProcedure;
cmd.CommandText = "Your Stored Procedure";
cmd.Parameters.Add("Your Parameter Name", SqlDbType.VarChar).Value = expression;
cmd.Connection = con;
using (IDataReader dr = cmd.ExecuteReader())
{
if (dr.Read())
{
}
}
}
While storing the data in Sql Server Keep the data format consistent and synchronized with the data format while retrieving....
Related
i need to fetch last modified date of item in table(oracle db).
in db format of modified date=04-DEC-20
while displaying in console modified date=04-09-2020
c# code to fetch modified date
string connString =DBUtils.GetDBConnection();
OracleConnection conn = new OracleConnection();
conn.ConnectionString = connString;
string sql = "select LASTMODIFIED , name from v_vname where name in('hector')";
OracleCommand cmd = new OracleCommand();
// Set connection for command.
cmd.Connection = conn;
cmd.CommandText = sql;
conn.Open();
using (DbDataReader reader = cmd.ExecuteReader())
{
if (reader.HasRows)
{
while (reader.Read())
{
int date = reader.GetOrdinal("LASTMODIFIED"); // 0
var LASTmTime = reader.GetValue(0);
Console.WriteLine("modifieddate:" + LASTmTime);
}
}
}
In Oracle, you can format a date as a string with to_char():
select to_char(lastmodified, 'dd-mm-yyyy') as last_modified, name
from v_vname
where name = 'hector'
Side note: name in ('hector') is simpler phrased name = 'hector'.
It's elegant when you use .ToString("dd-MM-yyyy") in C#
while (reader.Read())
{
int date = reader.GetOrdinal("LASTMODIFIED"); // 0
var LASTmTime = reader.GetValue(0).ToString("dd-MM-yyyy");
Console.WriteLine("modifieddate:" + LASTmTime);
}
DATE data-type values in Oracle are binary values consisting of 7-bytes (which are always century, year-of-century, month, day, hour, minute and second).
What you are seeing when you say the format is DD-MON-RR is the user interface you are using formatting the binary value as something that you, the user, will understand and for SQL/Plus (and SQL Developer and others) this will be based on the NLS_DATE_FORMAT session parameter and the default NLS_DATE_FORMAT value depends on which territory you say you are using when you setup the database.
What you need to do, is the output a string representation of the DATE formatted according to your requirements. You can either do this in SQL and use TO_CHAR to format the string:
SELECT TO_CHAR( LASTMODIFIED, 'DD-MM-YYYY' ) AS last_modified,
name
FROM v_vname
WHERE name = 'hector'
Or could do it in C#:
DateTime LASTmTime = reader.GetValue(0);
Console.WriteLine("modifieddate:" + LASTmTime.toString("dd-MM-yyyy"));
I have a birthdate column of type Date in sql database
And in my application I use a dateTimePicker to get the birth date
But when i am trying to insert the date taken from the dateTimePicker:
I get an error :
Incorrect syntax near '12'
And when I try to debug the code I find that the value taken from the dateTimePicker is
Date = {3/21/2015 12:00:00 AM}
The CODE:
//cmd is sql command
cmd.CommandText="INSERT INTO person (birthdate) VALUES("+dateTimePicker.Value.Date+")";
//con is sql connection
con.Open();
cmd.ExecuteNonQuery();
con.Close();
What you really should do is use parameters to avoid SQL injection attacks - and it also frees you from string formatting dates - also a good thing!
//cmd is sql command
cmd.CommandText = "INSERT INTO dbo.Person(birthdate) VALUES(#Birthdate);";
cmd.Parameters.Add("#Birthdate", SqlDbType.Date).Value = dateTimePicker.Value.Date;
//con is sql connection
con.Open();
cmd.ExecuteNonQuery();
con.Close();
Also, it's a recommend best practice to put your SqlConnection, SqlCommand and SqlDataReader into using(....) { .... } blocks to ensure proper disposal:
string connectionString = ".......";
string query = "INSERT INTO dbo.Person(birthdate) VALUES(#Birthdate);";
using (SqlConnection con = new SqlConnection(connectionString))
using (SqlCommand cmd = new SqlCommand(query, conn))
{
cmd.Parameters.Add("#Birthdate", SqlDbType.Date).Value = dateTimePicker.Value.Date;
con.Open();
cmd.ExecuteNonQuery();
con.Close();
}
As mentioned before the best practice is to use parameters, but if you really need to use a TSQL statement from source you should use date in the format: yyyymmdd
cmd.CommandText="INSERT INTO person (birthdate) VALUES('"+dateTimePicker.Value.Date.ToString("yyyyMMdd")+"')";
Try including quotes:
cmd.CommandText="INSERT INTO person (birthdate) VALUES('"+dateTimePicker.Value.Date+"')";
I'd recommend using parameters too.
Try this as string format:
cmd.CommandText="INSERT INTO person(birthdate)VALUES('"+dateTimePicker.Value.Date+"')";
dateTimePicker stores values as 1/1/1900 12:00:00 AM so you should use DATETIME if you're trying to store it since DATETIME's format is: YYYY-MM-DD HH:MI:SS.
You can print the dateTimePicker value using
MessageBox.Show(dateTimePicker.Value.ToString());
to see for yourself.
I use GETDATE() in a SQL Server stored procedure to insert a date into the SQL Server database table.
After that I need to implement a C# function which is based on datetime input parameter finds if the date was saved in the tables.
The datetime in C# and SQL are different. How do I convert from C# datetime to SQL datetime which has a form of yyyy-mm-ddT:yy:mm:ss.mmm? I need to specify explicitly yyyy-mm-ddT:yy:mm:ss.mmm.
Will be happy for all propositions/possible ways.
DateTime in .Net framework and SQL Server (if it is DateTime type field) is irrespective of the format. Format is only useful for displaying output.
If your field in SQL Server is of DateTime type then you can query it from C# code using parameterized query something like:
public DataTable GetRecords(DateTime dtParameter)
{
DataTable dt = null;
using (SqlConnection conn = new SqlConnection("connection string"))
{
using (SqlCommand cmd = new SqlCommand("SELECT * from yourTable where DateField = #dateparameter"))
{
conn.Open();
cmd.Parameters.AddWithValue("#dateparameter",dtParameter);
SqlDataReader dr = cmd.ExecuteReader();
//...rest of the code
dt.Load(dr);
}
}
return dt;
}
Datetimes between C# and SQL are 100% compatible. The format shouldn't make any difference if you are passing them as DateTimes. If you are generating a SQL string then I would highly recommend changing to SQL Parameters so you don;t have to worry about any formatting issues.
A datetime has no format at all, it has a value. SQL-DateTimes and C# DateTimes are compatible. So don't convert it (to string) at all but pass it as datetime-parameter to the database.
Then you're safe if the DateTime value is within SqlDateTime.MinValue(January 1, 1753) and SqlDateTime.MaxValue(December 31, 9999).
You should never write DateTime.Now from client code to insert into the database as this will be based on the clients local time; do this
public DateTime GetDatabaseTime()
{
var parameter = new SqlParameter("time", SqlDbType.DateTime2)
{
Direction = ParameterDirection.Output
};
using (var connection = new SqlConnection(ConnectionString))
{
connection.Open();
using (var command = new SqlConnection("SELECT #time = SYSDATETIME()", connection))
{
command.ExecuteNonQuery();
}
}
return (DateTime)parameter.Value;
}
Also you should never use DATETIME in SQL Server you should always use DATETIME2 as DATETIME is less accurate than C#::DateTime and it will lead to rounding errors. I know this from bitter experience.
If you are using Entity Framework, and your database is using datetime and not datetime2, the trick is to use SqlDateTime to match the fact that .Net goes to nanosecond, versus sql's millisecond precision. You can use your DateTime variable in .net.. for a SqlDateTime instance, and then you can uniquely identify a record down to the millisecond.
System.Data.SqlTypes.SqlDateTime entry2 = new System.Data.SqlTypes.SqlDateTime(new DateTime(dto.LookUpDateTime));
DateTime entry = entry2.Value;
var existticket = from db in context.Tickets
where db.LookupDateTime == entry && db.UserId == UserId
select db;
I am capturing the time in the text box (by using AJAX calender extender)
the time in the string is 12/10/2013, but when I assign the string to a datetime object it is converted into 12/10/2013 12:00:00 AM.
I want to use the date to filter the records in the database using the query below. Please help
string date1 = txtDate1.Text;
DateTime date = DateTime.ParseExact(txtDate1.Text, "MM/dd/yyyy",
System.Globalization.CultureInfo.InvariantCulture);
string strQuery = "SELECT Story.UserName,Story.StoryId,COUNT(Likes.StoryID) AS NumberOfOrders
FROM Likes LEFT JOIN Story ON Likes.StoryId=Story.StoryId and liked=" + date1 + "
GROUP BY Story.StoryId,Story.UserName order by NumberOfOrders DESC ;";
It's generally not a good idea to pass dates as strings in your queries because you will most likely run into formatting issues - leave it up to the Framework you are using decide on what the best format is.
In your circumstances, you can do this by using SqlParameters e.g.
DateTime date = DateTime.ParseExact(txtDate1.Text, "MM/dd/yyyy", CultureInfo.InvariantCulture);
string strQuery = "SELECT Story.UserName, Story.StoryId, COUNT(Likes.StoryID) AS NumberOfOrders
FROM Likes LEFT JOIN Story ON Likes.StoryId=Story.StoryId and liked=#dateTime
GROUP BY Story.StoryId,Story.UserName order by NumberOfOrders DESC";
using (SqlConnection connection = new SqlConnection("..."))
{
using (SqlCommand cmd = new SqlCommand(strQuery, connection))
{
cmd.Parameters.AddWithValue("#dateTime", date);
connection.Open();
SqlDataReader reader = cmd.ExecuteReader();
...
}
}
Another important reason to use parameters when writing raw SQL is to ensure your user input is correctly sanatized and safe to pass to the DB. Failure to do this can leave you open to various exploitations such as SQL Injection.
Instead of DateTime object you can use Date object.
DateTime is an integer interpreted to represent both parts of DateTime (ie: date and time). You will always have both date and time in DateTime.
ex:
DateTime.Now.ToString("MM/dd/yyyy");
How to convert C# datetime to MySql Datetime format. I am getting value from text box like 7/27/2011 this format. But i want to convert in this format 2011-7-27. So here i am stuking. Please help me. My objective is to filter the record between two dates and show in a listview control in asp.net.
Here is my code:
DateTime dt1 = Convert.ToDateTime(txtToDate.Text);
DateTime dt2 = Convert.ToDateTime(txtFromDate.Text);
lvAlert.DataSource = facade.GetAlertsByDate(dt1, dt2);
lvAlert.DataBind();
I haven't used MySQL with .NET, but Oracle has similar date conversion issues with .NET. The only way to stay snae with this has been to use parameters for date values, both for input as welll as for WHERE clause comparisons. A parameter created with a MySQL date parameter type, and just giving it a .NET datetime value, should work without needing you to do conversions.
EDITED TO ADD SAMPLE CODE
This code sample shows the basic technique of using parameters for DateTime values, instead of coding conversions to text values and embedding those text values directly in the SQL command text.
public DataTable GetAlertsByDate(DateTime start, DateTime end)
{
SqlConnection conn = new SqlConnection(connectionString);
SqlCommand cmd = new SqlCommand(
"SELECT * FROM Alerts WHERE EventTime BETWEEN #start AND #end", conn);
DataTable table = new DataTable();
try
{
SqlParameter param;
param = new SqlParameter("#start", SqlDbType.DateTime);
param.Value = start;
cmd.Parameters.Add(param);
param = new SqlParameter("#end", SqlDbType.DateTime);
param.Value = end;
cmd.Parameters.Add(param);
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(table);
}
finally
{
cmd.Dispose();
conn.Close();
conn.Dispose();
}
return table;
}
This is SQL Server code, but the technique should be the same for most databases. For Oracle, for example, the only changes would be to use Oracle data access objects, and use ":" in place of "#" in parameter names. The technique for MySQL should also be very similar.
For many databases, shortcuts may exist for creating parameters, such as:
cmd.Parameters.AddWithValue("#start", start);
This works when you know the value is not null, and the correct parameter type can be derived from the C# type of the value. "AddWithValue" is specific to SQL Server; "Add" works also but is obsolete in SQL Server.
Hope this helps.
You can assign format to data time, DateTime.ParseExact() or DateTime.ToString(format), :
the format for 2011-7-27 is yyyy-m-dd
Assuming you are doing this in the database I think you should use date_format to get in the required format
Something like date_format(dateval,'%Y-%c-%d') (Not tested)
I use:
string fieldate = dt1.ToString("yyyy-MM-dd");