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How to capture the date timestamp in Snowflake database in a C# console application? [duplicate]

I read a string using this format with a data reader. How can I read in a date using similar format?
while (MyReader.Read())
{
TextBox1.Text = (string)MyReader["Note"];
}

Try as given below:
while (MyReader.Read())
{
TextBox1.Text = Convert.ToDateTime(MyReader["DateField"]).ToString("dd/MM/yyyy");
}
in ToString() method you can change data format as per your requirement.

If the query's column has an appropriate type then
var dateString = MyReader.GetDateTime(MyReader.GetOrdinal("column")).ToString(myDateFormat)
If the query's column is actually a string then see other answers.

(DateTime)MyReader["ColumnName"];
OR
Convert.ToDateTime(MyReader["ColumnName"]);

This may seem slightly off topic but this was the post I came across when wondering what happens when you read a column as a dateTime in c#. The post reflects the information I would have liked to be able to find about this mechanism. If you worry about utc and timezones then read on
I did a little more research as I'm always very wary of DateTime as a class because of its automatic assumptions about what timezone you are using and because it is way too easy to confuse local times and utc times.
What I'm trying to avoid here is DateTime going 'oh look the computer I'm being run on is in timezone x, therefore this time must also be in timezone x, when I get asked for my values I'll reply as if I'm in that timezone'
I was trying to read a datetime2 column.
The date time you will get back from sql server will end up being of Kind.Unspecified this seems to mean it gets treated like UTC, which is what I wanted.
When reading a date column you also have to read it as a DateTime even though it has no time and is even more prone to screwing up by timezones (as it is on midnight).
I'd certainly consider this to be safer way of reading the DateTime as I suspect it can probably be modified by either settings in sql server or static settings in your c#:
var time = reader.GetDateTime(1);
var utcTime = new DateTime(time.Ticks, DateTimeKind.Utc);
From there you can get the components (Day, Month, Year) etc and format how you like.
If what you have is actually a date + a time then Utc might not be what you want there - since you are mucking around on the client you may need to convert it to a local time first (depending on what the meaning of the time is). However that opens up a whole can of worms.. If you need to do that I'd recommend using a library like noda time. There is TimeZoneInfo in the standard library but after briefly investigating it, it doesn't seem to have a proper set of timezones. You can see the list provided by TimeZoneInfo by using the method TimeZoneInfo.GetSystemTimeZones();
I also discovered sql server management studio doesn't convert times to local time before displaying them. Which is a relief!

I know that this is an old question, but I'm surprised that no answer mentions GetDateTime:
Gets the value of the specified column as a DateTime object.
Which you can use like:
while (MyReader.Read())
{
TextBox1.Text = MyReader.GetDateTime(columnPosition).ToString("dd/MM/yyyy");
}

/// <summary>
/// Returns a new conContractorEntity instance filled with the DataReader's current record data
/// </summary>
protected virtual conContractorEntity GetContractorFromReader(IDataReader reader)
{
return new conContractorEntity()
{
ConId = reader["conId"].ToString().Length > 0 ? int.Parse(reader["conId"].ToString()) : 0,
ConEmail = reader["conEmail"].ToString(),
ConCopyAdr = reader["conCopyAdr"].ToString().Length > 0 ? bool.Parse(reader["conCopyAdr"].ToString()) : true,
ConCreateTime = reader["conCreateTime"].ToString().Length > 0 ? DateTime.Parse(reader["conCreateTime"].ToString()) : DateTime.MinValue
};
}
OR
/// <summary>
/// Returns a new conContractorEntity instance filled with the DataReader's current record data
/// </summary>
protected virtual conContractorEntity GetContractorFromReader(IDataReader reader)
{
return new conContractorEntity()
{
ConId = GetValue<int>(reader["conId"]),
ConEmail = reader["conEmail"].ToString(),
ConCopyAdr = GetValue<bool>(reader["conCopyAdr"], true),
ConCreateTime = GetValue<DateTime>(reader["conCreateTime"])
};
}
// Base methods
protected T GetValue<T>(object obj)
{
if (typeof(DBNull) != obj.GetType())
{
return (T)Convert.ChangeType(obj, typeof(T));
}
return default(T);
}
protected T GetValue<T>(object obj, object defaultValue)
{
if (typeof(DBNull) != obj.GetType())
{
return (T)Convert.ChangeType(obj, typeof(T));
}
return (T)defaultValue;
}

In my case I changed the datetime field in the SQL database to not allow null. SqlDataReader then allowed me to cast the value directly to a DateTime.

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;
namespace Library
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
private void button1_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\NIKHIL R\Documents\Library.mdf;Integrated Security=True;Connect Timeout=30");
string query = "INSERT INTO [Table] (BookName , AuthorName , Category) VALUES('" + textBox1.Text.ToString() + "' , '" + textBox2.Text.ToString() + "' , '" + textBox3.Text.ToString() + "')";
SqlCommand com = new SqlCommand(query, con);
con.Open();
com.ExecuteNonQuery();
con.Close();
MessageBox.Show("Entry Added");
}
private void button3_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\NIKHIL R\Documents\Library.mdf;Integrated Security=True;Connect Timeout=30");
string query = "SELECT * FROM [TABLE] WHERE BookName='" + textBox1.Text.ToString() + "' OR AuthorName='" + textBox2.Text.ToString() + "'";
string query1 = "SELECT BookStatus FROM [Table] where BookName='" + textBox1.Text.ToString() + "'";
string query2 = "SELECT DateOfReturn FROM [Table] where BookName='" + textBox1.Text.ToString() + "'";
SqlCommand com = new SqlCommand(query, con);
SqlDataReader dr, dr1,dr2;
con.Open();
com.ExecuteNonQuery();
dr = com.ExecuteReader();
if (dr.Read())
{
con.Close();
con.Open();
SqlCommand com1 = new SqlCommand(query1, con);
com1.ExecuteNonQuery();
dr1 = com1.ExecuteReader();
dr1.Read();
string i = dr1["BookStatus"].ToString();
if (i =="1" )
{
con.Close();
con.Open();
SqlCommand com2 = new SqlCommand(query2, con);
com2.ExecuteNonQuery();
dr2 = com2.ExecuteReader();
dr2.Read();
MessageBox.Show("This book is already issued\n " + "Book will be available by "+ dr2["DateOfReturn"] );
}
else
{
con.Close();
con.Open();
dr = com.ExecuteReader();
dr.Read();
MessageBox.Show("BookFound\n" + "BookName=" + dr["BookName"] + "\n AuthorName=" + dr["AuthorName"]);
}
con.Close();
}
else
{
MessageBox.Show("This Book is not available in the library");
}
}
private void button2_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\NIKHIL R\Documents\Library.mdf;Integrated Security=True;Connect Timeout=30");
string query = "SELECT * FROM [TABLE] WHERE BookName='" + textBox1.Text.ToString() + "'";
string dateofissue1 = DateTime.Today.ToString("dd-MM-yyyy");
string dateofreturn = DateTime.Today.AddDays(15).ToString("dd-MM-yyyy");
string query1 = "update [Table] set BookStatus=1,DateofIssue='"+ dateofissue1 +"',DateOfReturn='"+ dateofreturn +"' where BookName='" + textBox1.Text.ToString() + "'";
con.Open();
SqlCommand com = new SqlCommand(query, con);
SqlDataReader dr;
com.ExecuteNonQuery();
dr = com.ExecuteReader();
if (dr.Read())
{
con.Close();
con.Open();
string dateofissue = DateTime.Today.ToString("dd-MM-yyyy");
textBox4.Text = dateofissue;
textBox5.Text = DateTime.Today.AddDays(15).ToString("dd-MM-yyyy");
SqlCommand com1 = new SqlCommand(query1, con);
com1.ExecuteNonQuery();
MessageBox.Show("Book Isuued");
}
else
{
MessageBox.Show("Book Not Found");
}
con.Close();
}
private void button4_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=C:\Users\NIKHIL R\Documents\Library.mdf;Integrated Security=True;Connect Timeout=30");
string query1 = "update [Table] set BookStatus=0 WHERE BookName='"+textBox1.Text.ToString()+"'";
con.Open();
SqlCommand com = new SqlCommand(query1, con);
com.ExecuteNonQuery();
string today = DateTime.Today.ToString("dd-MM-yyyy");
DateTime today1 = DateTime.Parse(today);
string query = "SELECT dateofReturn from [Table] where BookName='" + textBox1.Text.ToString() + "'";
con.Close();
con.Open();
SqlDataReader dr;
SqlCommand cmd = new SqlCommand(query, con);
cmd.ExecuteNonQuery();
dr = cmd.ExecuteReader();
dr.Read();
string DOR = dr["DateOfReturn"].ToString();
DateTime dor = DateTime.Parse(DOR);
TimeSpan ts = today1.Subtract(dor);
string query2 = "update [Table] set DateOfIssue=NULL, DateOfReturn=NULL WHERE BookName='" + textBox1.Text.ToString() + "'";
con.Close();
con.Open();
SqlCommand com2 = new SqlCommand(query2, con);
com2.ExecuteNonQuery();
int x = int.Parse(ts.Days.ToString());
if (x > 0)
{
int fine = x * 5;
textBox6.Text = fine.ToString();
MessageBox.Show("Book Received\nFine=" + fine);
}
else
{
textBox6.Text = "0";
MessageBox.Show("Book Received\nFine=0");
}
con.Close();
}
}
}

How to store Arabic language values from web-service in database

I'm trying to store some Arabic values I got from a web service, but when I select them from the database and show them in a DataGridView it just shows "?????". The three columns in the database are nvarchar(50). How should I be storing them?
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml;
using System.Data.SqlClient;
namespace WindowsApplication1
{
public partial class Form1 : Form
{
string user = "gamal";
string p1 = "GAM123";
string p2 = "GAM123";
string sdate = "05152014000000";
string edate = "05182014235959";
string node = "232641";
string group = "Al Ahsa - ???????";
string Compress = "";
string m_d = "sa";
string lang = "1";
DataSet ds = new DataSet();
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
test_ws.ppppWebServiceSoapClient ws =
new test_ws.ppppWebServiceSoapClient("pppp Report Web ServiceSoap");
ds = ws.GetGroups(user, p1, p2);
DataSet ds_ra = new DataSet();
ds_ra = ws.RegionAlarm(user, p1, p2, sdate, edate, node, group, Compress, m_d, lang);
ds_ra.WriteXml("region_alarm.xml");
string connetionString = null;
SqlConnection connection;
SqlCommand command ;
SqlDataAdapter adpter = new SqlDataAdapter();
string sql = null;
string ID = null;
string nodegroup = null;
string nodecount = null;
connetionString = #"Server=.\SQLEXPRESS; DataBase=hhhh; Integrated Security=True;";
connection = new SqlConnection(connetionString);
int i = 0;
connection.Open();
for (i = 0; i <= ds.Tables[0].Rows.Count - 1; i++)
{
ID = ds.Tables[0].Rows[i].ItemArray[0].ToString();
nodegroup = ds.Tables[0].Rows[i].ItemArray[1].ToString();
nodecount = ds.Tables[0].Rows[i].ItemArray[2].ToString();
sql = "insert into groups (id,nodegroup,nodecount)
values(" + ID + ",'" + nodegroup + "'," + nodecount + ")";
command = new SqlCommand(sql, connection);
adpter.InsertCommand = command;
adpter.InsertCommand.ExecuteNonQuery();
}
sql = "select * from groups";
command = new SqlCommand(sql, connection);
adpter.SelectCommand = command;
adpter.SelectCommand.ExecuteNonQuery();
DataTable dt = new DataTable();
adpter.Fill(dt);
dataGridView1.DataSource = dt;
connection.Close();
MessageBox.Show("Done ..تم ");
}
}
}

After ensuring the NodeGroup column in your table is an NVARCHAR(), use parameters instead of concatenation, for both preventing SQL injection, and to make sure your data types are properly set. When you were concatenating the sql, the string literal was a varchar, unless you put an N in front of the literal.
sql = "insert into groups (id,nodegroup,nodecount)
values(#ID,#NodeGroup, #NodeCount)";
command = new SqlCommand(sql, connection);
command.Parameters.AddWithValue("#ID", id);
command.Parameters.AddWithValue("#NodeGroup", nodegroup);
command.Parameters.AddWithValue("#NodeCroup", nodecount);
adpter.InsertCommand = command;
adpter.InsertCommand.ExecuteNonQuery();

Change this:
values(" + ID + ",'" + nodegroup + "'," + nodecount + ")";
into
values(" + ID + ", N'" + nodegroup + "'," + nodecount + ")";
However, you should really be using parameters instead of building an SQL string with the values in it. That will get you around all of the escaping issues.

When inserting in to database with inline sql you have to prefix the nvarchar value with 'N'. For example: insert into mytable (col1) values (N'myvalue')

How to create new database upon reopening application?

I have a log viewing application that writes log statements to a database and then sends them from the database to the log viewer GUI. I want to be able to open more than one instance of the log viewer but when I do it will be creating a database with the same name as the previous instance of the viewer. I've tried creating a database with a different name if one has already been created but that doesn't seem to work. Any suggestions? Here's the code for creating/accessing/destroying databases:
public class Database
{
public bool hasAdminPriv
{
get;
set;
}
public bool hasBeenCreated
{
get;
set;
}
public Database()
{
hasAdminPriv = true;
//Construction checks to see if user has Admin priveleges
bool isElevated;
WindowsIdentity identity = WindowsIdentity.GetCurrent();
WindowsPrincipal principal = new WindowsPrincipal(identity);
isElevated = principal.IsInRole(WindowsBuiltInRole.Administrator);
if (!isElevated)
hasAdminPriv = false;
}
//returns true if the database creation was successful
public bool CreateDatabase()//creates a database dynamically by making a query request to the server
{
String str;
SqlConnection myConn = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS; Initial Catalog=Master;Integrated Security=True");
str = "CREATE DATABASE MyDatabase ON PRIMARY " +
"(NAME = MyDatabase_Data, " +
"FILENAME = 'C:\\Program Files (x86)\\Microsoft SQL Server\\MSSQL.1\\MSSQL\\Data\\MyDatabaseData.mdf', " +
"SIZE = 30MB, MAXSIZE = 10GB, FILEGROWTH = 20%) " +
"LOG ON (NAME = MyDatabase_Log, " +
"FILENAME = 'C:\\Program Files (x86)\\Microsoft SQL Server\\MSSQL.1\\MSSQL\\Data\\MyDatabaseLog.ldf', " +
"SIZE = 10MB, " +
"MAXSIZE = 1GB, " +
"FILEGROWTH = 10%)";
SqlCommand myCommand = new SqlCommand(str, myConn);
try
{
myConn.Open();
myCommand.ExecuteNonQuery();
}
catch (System.Exception ex)
{
int done = 0;
while (done < 10)
{
String str2 = "CREATE DATABASE" + done + " MyDatabase ON PRIMARY " +
"(NAME = MyDatabase_Data, " +
"FILENAME = 'C:\\Program Files (x86)\\Microsoft SQL Server\\MSSQL.1\\MSSQL\\Data\\MyDatabaseData.mdf', " +
"SIZE = 30MB, MAXSIZE = 10GB, FILEGROWTH = 20%) " +
"LOG ON (NAME = MyDatabase_Log, " +
"FILENAME = 'C:\\Program Files (x86)\\Microsoft SQL Server\\MSSQL.1\\MSSQL\\Data\\MyDatabaseLog.ldf', " +
"SIZE = 10MB, " +
"MAXSIZE = 1GB, " +
"FILEGROWTH = 10%)";
SqlCommand myCommand2 = new SqlCommand(str2, myConn);
try{
myCommand2.ExecuteNonQuery();
}
catch{
++done;
}
myConn.Close();
hasBeenCreated = true;
return true;
}
return false;
}
finally
{
if (myConn.State == ConnectionState.Open)
{
myConn.Close();
}
}
hasBeenCreated = true;
return true;
}
//Creates the table in the database by a query request
//a return value of true means Database was created succesfully
public bool CreateTable()
{
SqlConnection myConn = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS; Initial Catalog=MyDatabase;Integrated Security=True");
string createString = "CREATE TABLE storage (ID INT NOT NULL, Level varchar(255) , LevelInt INT, DateTime varchar(255),Counter smallint,Device varchar(255), Source varchar(255), Description varchar(255),PRIMARY KEY (ID))"; //YOUR SQL COMMAND TO CREATE A TABLE
SqlCommand create = new SqlCommand(createString, myConn);
myConn.Open();
create.ExecuteNonQuery();
myConn.Close();
return true;
}
//Add the element's values to the database/table to later recall/reorder
public bool addElement(LogParse log,int num)
{
SqlConnection con = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=True");
try
{
con.Open();
SqlCommand cmd = new SqlCommand("Insert into storage(ID, Level, LevelInt, DateTime, Counter, Device, Source, Description) values(" + num + ",#Level, #LevelInt, #DataTimeItem,#counterItem,#deviceItem,#sourceItem,#descItem)", con);
cmd.Parameters.AddWithValue("#Level", log.Level);
cmd.Parameters.AddWithValue("#LevelInt", log.LevelInt);
cmd.Parameters.AddWithValue("#DataTimeItem", log.TimeStamp);
cmd.Parameters.AddWithValue("#counterItem", log.SequentialNumber);
cmd.Parameters.AddWithValue("#deviceItem", log.Device);
cmd.Parameters.AddWithValue("#sourceItem", log.Source);
cmd.Parameters.AddWithValue("#descItem", log.Description);
cmd.ExecuteNonQuery();
con.Close();
}
catch (Exception ee)
{
return false;
}
return true;
}
//outputs a string array with all the values in the database
public LogParse[] readValue(int start, int end)
{
SqlConnection con = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=True");
con.Open();
LogParse[] s = new LogParse[end - start];
try
{
using (var oCommand = new SqlCommand("SELECT * From storage WHERE ID BETWEEN #Start AND #End", con))
{
oCommand.Parameters.AddWithValue("#Start", start);
oCommand.Parameters.AddWithValue("#End", end);
using (var oReader = oCommand.ExecuteReader())
{
int i = 0;
while (oReader.Read() && i < end-start)
{
//s[i] = oReader.GetString(1) + oReader.GetString(2) + oReader.GetString(3);
String Level = oReader.GetString(1);
Int32 LevelInt = oReader.GetInt32(2);
String Datetime = oReader.GetString(3);
Int16 SequentialNumber = (Int16)oReader.GetValue(4);
String Device = oReader.GetString(5);
String Source = oReader.GetString(6);
String Description = oReader.GetString(7);
s[i] = new LogParse();
s[i].Level = Level;
s[i].LevelInt = LevelInt;
s[i].TimeStamp = DateTime.Parse(Datetime);
s[i].SequentialNumber = SequentialNumber;
s[i].Device = Device;
s[i].Description = Description;
s[i].Source = Source;
++i;
}
}
}
}
catch
{
}
con.Close();
return s;
}
//Deletes the database by a query statement
//a return value of true means the delete was succesful
public static bool deleteDatabase()
{
String str;
SqlConnection myConn = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS; Initial Catalog=Master;Integrated Security=True");
str = #"ALTER DATABASE MyDatabase SET SINGLE_USER WITH ROLLBACK IMMEDIATE;DROP DATABASE [MyDatabase]";
SqlCommand myCommand = new SqlCommand(str, myConn);
try
{
myConn.Open();
myCommand.ExecuteNonQuery();
}
catch (System.Exception ex)
{
return false;
}
finally
{
if (myConn.State == ConnectionState.Open)
{
myConn.Close();
}
}
return true;
}
}

DON'T create another database, or table, it's evil. Just add Instance ID into table storage. And when writing new logs just add instance ID, same goes when reading from DB, put instance ID into where clause.
Another issue is to pick good Instance ID, your scenario is not very clear to me, but if you want every new application instance to have separate data, just create new GUID and use it as Instance ID.
For example you can have static property InstanceID in your Database class, and your class could look something like this :
public class Database
{
public static Guid InstanceID = new Guid();
//Add the element's values to the database/table to later recall/reorder
public bool addElement(LogParse log,int num)
{
SqlConnection con = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=True");
try
{
con.Open();
SqlCommand cmd = new SqlCommand("Insert into storage(ID, InstanceID, Level, LevelInt, DateTime, Counter, Device, Source, Description) values(" + num + ",#Level, #LevelInt, #DataTimeItem,#counterItem,#deviceItem,#sourceItem,#descItem)", con);
// writing InstanceID
cmd.Parameters.AddWithValue("#InstanceID", Database.InstanceID);
cmd.Parameters.AddWithValue("#Level", log.Level);
cmd.Parameters.AddWithValue("#LevelInt", log.LevelInt);
cmd.Parameters.AddWithValue("#DataTimeItem", log.TimeStamp);
cmd.Parameters.AddWithValue("#counterItem", log.SequentialNumber);
cmd.Parameters.AddWithValue("#deviceItem", log.Device);
cmd.Parameters.AddWithValue("#sourceItem", log.Source);
cmd.Parameters.AddWithValue("#descItem", log.Description);
cmd.ExecuteNonQuery();
con.Close();
}
catch (Exception ee)
{
return false;
}
return true;
}
//outputs a string array with all the values in the database
public LogParse[] readValue(int start, int end)
{
SqlConnection con = new SqlConnection("Data Source=" + Environment.UserName + "-D1SD\\SQLEXPRESS;Initial Catalog=MyDatabase;Integrated Security=True");
con.Open();
LogParse[] s = new LogParse[end - start];
try
{
// select with InstanceID
using (var oCommand = new SqlCommand("SELECT * From storage WHERE InstanceID = #InsID ID BETWEEN #Start AND #End", con))
{
oCommand.Parameters.AddWithValue("#Start", start);
oCommand.Parameters.AddWithValue("#End", end);
oCommand.Parameters.AddWithValue("#InsID", Database.InstanceID);
using (var oReader = oCommand.ExecuteReader())
{
int i = 0;
while (oReader.Read() && i < end-start)
{
//s[i] = oReader.GetString(1) + oReader.GetString(2) + oReader.GetString(3);
String Level = oReader.GetString(1);
Int32 LevelInt = oReader.GetInt32(2);
String Datetime = oReader.GetString(3);
Int16 SequentialNumber = (Int16)oReader.GetValue(4);
String Device = oReader.GetString(5);
String Source = oReader.GetString(6);
String Description = oReader.GetString(7);
s[i] = new LogParse();
s[i].Level = Level;
s[i].LevelInt = LevelInt;
s[i].TimeStamp = DateTime.Parse(Datetime);
s[i].SequentialNumber = SequentialNumber;
s[i].Device = Device;
s[i].Description = Description;
s[i].Source = Source;
++i;
}
}
}
}
catch
{
}
con.Close();
return s;
}
}
btw. DON'T swallow exceptions ! I leave your code the same but please don't do that, it's also evil, another thing is if there is a exception in your addElement method your connection will not be closed, use Using statement.

that doesn't sound safe at all, maybe one database with several user tables to store the logfiles for each user, but this just doesn't sound right to me.
otherwise a variable that is assigned randomly when the application is started in place of the database name when it is created.
but if you do something wrong there are going to be a lot of databases out there, but it looks like you have figured out sizing and some other things to keep them from overpowering the server machine.
Additional Information from Comment
if you are going to use tables on the Database(which I think is what you really need) then create the database separate and then create randomly named tables inside your application every time it is opened, you may want to have another table that would keep track of the the tables and the times they were opened as well, perhaps even what user opened them and such things like that

reading one record from access in C#

My requirement is to read Date column from access file and use one value to append it to a file name, so as to create file with date timestamp using the db value.
I am trying following approach but it gives me exception "No data exists for the row/column":
here's the code
OleDbConnection conn = new OleDbConnection(connectionString);
OleDbConnection conn1 = new OleDbConnection(connectionString);
string dt = "SELECT top 1 Date FROM Events";
OleDbCommand cmd1 = new OleDbCommand(dt, conn1);
conn1.Open();
OleDbDataReader rdr = cmd1.ExecuteReader();
string time_stmp = rdr.GetInt32(0).ToString();
rdr.Close();
conn1.Close();
string path = text_dir + "\\" + time_stmp + "_" + "BWC_Ejournal.txt";

You'll need to call the Read() method on the OleDbDataReader object before accessing its data.
E.g.
OleDbDataReader rdr = cmd1.ExecuteReader();
string time_stmp = "";
if(rdr.Read())
{
time_stmp = rdr.GetInt32(0).ToString();
}
else
{
//handle no data situation here
}
This will also allow to handle a situation where no data is returned more gracefully too.

DATE is a reserved word in ACE/Jet SQL. Try this instead:
string dt = "SELECT TOP 1 [Date] FROM Events";
Edit
On taking a closer look at your code I notice that you create the OleDbCommand object before the connection is opened. I've seen that cause problems as well. FWIW, the following code works for me:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.OleDb;
namespace oleDbTest
{
class Program
{
static void Main(string[] args)
{
using (var con = new OleDbConnection(
"Provider=Microsoft.ACE.OLEDB.12.0;" +
#"Data Source=C:\__tmp\main.accdb;"))
{
con.Open();
using (var cmd = new OleDbCommand(
"SELECT TOP 1 [Date] FROM [Events]", con))
{
string time_stmp = Convert.ToDateTime(cmd.ExecuteScalar()).ToString("yyyyMMdd");
Console.WriteLine(time_stmp.ToString());
}
con.Close();
}
Console.WriteLine("Done.");
System.Threading.Thread.Sleep(2000);
}
}
}

How do I connect to a database and loop over a recordset in C#?

What's the simplest way to connect and query a database for a set of records in C#?

#Goyuix -- that's excellent for something written from memory.
tested it here -- found the connection wasn't opened. Otherwise very nice.
using System.Data.OleDb;
...
using (OleDbConnection conn = new OleDbConnection())
{
conn.ConnectionString = "Provider=sqloledb;Data Source=yourServername\\yourInstance;Initial Catalog=databaseName;Integrated Security=SSPI;";
using (OleDbCommand cmd = new OleDbCommand())
{
conn.Open();
cmd.Connection = conn;
cmd.CommandText = "Select * from yourTable";
using (OleDbDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
Console.WriteLine(dr["columnName"]);
}
}
}
}

Very roughly and from memory since I don't have code on this laptop:
using (OleDBConnection conn = new OleDbConnection())
{
conn.ConnectionString = "Whatever connection string";
using (OleDbCommand cmd = new OleDbCommand())
{
cmd.Connection = conn;
cmd.CommandText = "Select * from CoolTable";
using (OleDbDataReader dr = cmd.ExecuteReader())
{
while (dr.Read())
{
// do something like Console.WriteLine(dr["column name"] as String);
}
}
}
}

That's definitely a good way to do it. But you if you happen to be using a database that supports LINQ to SQL, it can be a lot more fun. It can look something like this:
MyDB db = new MyDB("Data Source=...");
var q = from db.MyTable
select c;
foreach (var c in q)
Console.WriteLine(c.MyField.ToString());

This is an alternative way (DataReader is faster than this one):
string s = "";
SqlConnection conn = new SqlConnection("Server=192.168.1.1;Database=master;Connect Timeout=30;User ID=foobar;Password=raboof;");
SqlDataAdapter da = new SqlDataAdapter("SELECT TOP 5 name, dbid FROM sysdatabases", conn);
DataTable dt = new DataTable();
da.Fill(dt);
for (int i = 0; i < dt.Rows.Count; i++)
{
s += dt.Rows[i]["name"].ToString() + " -- " + dt.Rows[i]["dbid"].ToString() + "\n";
}
MessageBox.Show(s);

If you are intending on reading a large number of columns or records it's also worth caching the ordinals and accessing the strongly-typed methods, e.g.
using (DbDataReader dr = cmd.ExecuteReader()) {
if (dr.Read()) {
int idxColumnName = dr.GetOrdinal("columnName");
int idxSomethingElse = dr.GetOrdinal("somethingElse");
do {
Console.WriteLine(dr.GetString(idxColumnName));
Console.WriteLine(dr.GetInt32(idxSomethingElse));
} while (dr.Read());
}
}

If you are querying a SQL Server database (Version 7 and up) you should replace the OleDb classes with corresponding classes in the System.Data.SqlClient namespace (SqlConnection, SqlCommand and SqlDataReader) as those classes have been optimized to work with SQL Server.
Another thing to note is that you should 'never' select all as this might lead to unexpected results later on if you add or remove columns to this table.

I guess, you can try entity framework.
using (SchoolDBEntities ctx = new SchoolDBEntities())
{
IList<Course> courseList = ctx.GetCoursesByStudentId(1).ToList<Course>();
//do something with courselist here
}

Charge the libraries
using MySql.Data.MySqlClient;
This is the connection:
public static MySqlConnection obtenerconexion()
{
string server = "Server";
string database = "Name_Database";
string Uid = "User";
string pwd = "Password";
MySqlConnection conect = new MySqlConnection("server = " + server + ";" + "database =" + database + ";" + "Uid =" + Uid + ";" + "pwd=" + pwd + ";");
try
{
conect.Open();
return conect;
}
catch (Exception)
{
MessageBox.Show("Error. Ask the administrator", "An error has occurred while trying to connect to the system", MessageBoxButtons.OK, MessageBoxIcon.Error);
return conect;
}
}