Develop Reference

Error one or more parameters is required

This is C# code and giving me an error that one or more parameters are required in the access database can anyone help me?...I am hanged due to this error!
Here's the code:
string date = textBox1.Text;
con = new OleDbConnection(cs);
con.Open();
String sql = "SELECT * From Sales where InvoiceDate = date ";
cmd = new OleDbCommand(sql, con);
cmd.ExecuteNonQuery();
DataTable dt = new DataTable();
dt.Load(cmd.ExecuteReader());
dataGridView1.DataSource = dt;

First I recommend parsing that date to a DateTime as I hope your InvoiceDate is an actual date type in the DB. Second you need to use a parameter to pass in the value. Finally remove that ExecuteNonQuery. Also you should put disposable items into using statements so the connection will be closed properly.
DateTime date;
if(!DateTime.TryParse(textBox1.Text, out date))
{
//Do whatever you need to indicate a bad date.
}
using(var con = new OleDbConnection(cs))
{
con.Open();
String sql = "SELECT * From Sales where InvoiceDate = #date";
using(var cmd = new OleDbCommand(sql, con))
{
cmd.Parameters.Add("#date", /*Insert correct type here*/).Value = date;
DataTable dt = new DataTable();
dt.Load(cmd.ExecuteReader());
dataGridView1.DataSource = dt;
}
}

First flaw : You didn't mention what cs is(i mean show us the connection string) but not much of a big issue as it is not throwing the error.
Second flaw : InvoiceDate = date , here date is neither a value nor a variable.
To use it as a variable
...InvoiceDate ='" + date + "'"
To use it as direct value
...InvoiceDate ='date'"
Third Flaw : cmd.ExecuteNonQuery , it is unnecessary.
Fourth flaw : Well, i shouldn't call it a flaw,rather a bit of knowledge sharing : You can create a separate DataAdapter and then use it to populate your table :
OleDbDataAdapter ada = new OleDbDataAdapter(cmd);
ada.Fill(mydatatable);
Biggest flaw : Sql-Injection , please don't make it easy for attackers.Rather use parameters:
"SELECT * From Sales where InvoiceDate=#date"
cmd.Parameters.Add("#date", OleDbType.Varchar).Vale = dateStringHere ///change data-type from varchar as required

How to convert C# DateTime to MySQL timestamp table column

I'm trying to update a table element of type timestamp called dtprint with the current time (the original value is NULL). The code that I am using is as follows:
MySqlConnection con = new MySqlConnection("Connection_String");
con.Open();
MySqlCommand _cmd = con.CreateCommand();
string dt = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
_cmd.CommandText = "UPDATE requests SET dtprint = " + dt + " WHERE idPerson = " + _personID[index];
_cmd.ExecuteNonQuery();
con.Close();
The exception I keep getting is: Additional information: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '14:03:23 WHERE idPerson = 45' at line 1.
The only thing I can think of is that the Database isn't recognizing the time as a timestamp, any help is greatly appreciated.

Since dt is a string and your dtprint is timestamp, you need to use single quotes when you try to insert it. Like;
"UPDATE requests SET dtprint = '" + dt + "' WHERE
But don't use this way.
You should always use parameterized queries. This kind of string concatenations are open for SQL Injection attacks.
Also use using statement to dispose your database connections and objects.
using(MySqlConnection con = new MySqlConnection(ConnectionString))
using(MySqlCommand _cmd = con.CreateCommand())
{
string dt = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
_cmd.CommandText = #"UPDATE requests SET dtprint = #dtprint
WHERE idPerson = #id";
_cmd.Parameters.Add("#dtprint", MySqlType.TimeStamp).Value = dt;
_cmd.Parameters.Add("#id", MySqlType.Int).Value = _personID[index];
con.Open();
_cmd.ExecuteNonQuery();
}

Execute Datetime from C# to date in SQL Server 2008

I'm new in programming and want you to help me.
I have field of type (date) and when I insert data to database from my website in visual studio 2010 with C#, it Shows me an error during execution.
Can anyone help me?
Thank you
Code behind
string InsMus = "Insert into StoreMus (MusNo,MusDate)" +
"Values (" + Convert.ToInt16(txtMusNo.Text) + ",'" + DateTime.Parse(txtMusDate.Text) + "')";
cmd = new SqlCommand(InsMus , con);
con.Open();
cmd.ExecuteNonQuery();
con.Close();

Don't use string concanation to prevent sql injection. I'm sure that it will also fix this issue.
string InsMus = #"Insert into StoreMus (MusNo,MusDate)
Values (#MusNo, #MusDate);";
using(var con = new SqlConnection("Connection String..."))
using(var cmd = new SqlCommand(InsMus, con))
{
cmd.Parameters.Add("#MusNo", SqlDbType.SmallInt).Value = short.Parse(txtMusNo.Text);
cmd.Parameters.Add("#MusDate", SqlDbType.Date).Value = DateTime.Parse(txtMusDate.Text);
con.Open();
int inserted = cmd.ExecuteNonQuery();
}
Note that i've used the using-statement to ensure that the connection gets disposed/closed.
You could also use DateTime.TryParse instead of DateTime.Parse to prevent an exception that happens when the format of the date is invalid:
DateTime musDate;
if(!DateTime.TryParse(txtMusDate.Text, out musDate))
{
MessageBox.Show("Please enter a valid mus-date.");
return;
}
// here you can use musDate

asp.net error: Cannot implicitly convert type 'object' to 'string'. An explicit conversion exists (are you missing a cast?)

I want to retrieve data from a table in sql server called hotel using select WHERE statement and I get the above error. Can anyone help?
SqlConnection cnn = new
SqlConnection(ConfigurationManager.ConnectionStrings["myConnectionString"].ToString());
cnn.Open();
SqlCommand cmd = new SqlCommand();
cmd.CommandText = "SELECT RoomsAvailable FROM Hotel WHERE HotelName = '" +
this.DropDownList1.Text + "'";
cmd.Connection = cnn;
SqlDataAdapter da = new SqlDataAdapter();
da.SelectCommand = cmd;
DataSet ds = new DataSet();
da.Fill(ds, "Hotel");
SqlCommandBuilder cb = new SqlCommandBuilder(da);
DataRow dsRow = null;
foreach (DataRow dsRow_loopVariable in ds.Tables["Hotel"].Rows)
{
dsRow = dsRow_loopVariable;
//This line is where the error comes in.
this.txtHotel.Text = (dsRow["RoomsAvailable"]);
}

Change
this.txtHotel.Text = (dsRow["RoomsAvailable"]);
To
this.txtHotel.Text = (dsRow["RoomsAvailable"].ToString());

Or change to
this.txtHotel.Text = dsRow["RoomsAvailable"] as string;
and you won't get an exception if the value is null.

Try this Code
this.txtHotel.Text = Convert.ToString (dsRow["RoomsAvailable"]);

dsRow["RoomsAvailable"] Is an object of type DataRow, if you want the String value you need to call ToString():
this.txtHotel.Text = (dsRow["RoomsAvailable"].ToString());
Docs

Well i saw this code
cmd.CommandText = "SELECT RoomsAvailable FROM Hotel WHERE HotelName = '" +
this.DropDownList1.Text + "'";
and this.DropDownList1.Text will fetch you selected value not text .
just have you given HotelNames as dropdown values ?
and for error
Try
Convert.ToString(dsRow ["RoomsAvailable"]);

Conversion failed when converting date and/or time from character string 4

Not certain what I need to do here ... I have a SQL statement in a SqlCommand that works:
SqlCommand cmd = new SqlCommand("select * from fb_results where fb_date between '20130501' and '20130629' and fb_response = 'Yes' Order by fb_date, fb_login", conn);
Now I want to substitute a query string parameter for the hard coded date.
Here is my code:
string arg1 = Request.QueryString["date1"];
string arg2 = Request.QueryString["date2"];
DateTime dt1 = Convert.ToDateTime(arg1);
DateTime dt2 = Convert.ToDateTime(arg2);
string cvt1 = "'"+dt1.Year.ToString() + dt1.Month.ToString() + dt1.Day.ToString()+"'";
string cvt2 = "'"+dt2.Year.ToString() + dt2.Month.ToString() + dt2.Day.ToString()+"'";
string qry = "select * from fb_results where fb_date between " + cvt1 + " and " + cvt2;
SqlConnection conn = new SqlConnection(Sitecore.Configuration.Settings.GetConnectionString("feedback"));
SqlCommand cmd = new SqlCommand(qry, conn);
//SqlCommand cmd = new SqlCommand("select * from fb_results where fb_date between '20130501' and '20130629' and fb_response = 'Yes' Order by fb_date, fb_login", conn);
DataSet ds = new DataSet();
SqlDataAdapter da = new SqlDataAdapter(cmd);
da.Fill(ds);
GridView1.DataSource = ds;
GridView1.DataBind();
conn.Close();
I am getting an error
Conversion failed when converting date and/or time from character string.
What can I do to correct this? Thank you for any assistance.
Regards,

Try using parameterized queries and DateTime.TryParse.
DateTime dt1;
DateTime dt2;
if(!DateTime.TryParse(arg1, out dt1) && !DateTime.TryParse(arg2, out dt2))
{
// Handle error
}
const string query = "select * from fb_results where fb_date between #from and #to";
var command = new SqlCommand(query, connection);
command.Parameters.AddWithValue("#from", dt1);
command.Parameters.AddWithValue("#to", dt2);

Convert.ToDateTime(string) expects a format supported by the current culture. If you're using yyyyMMdd, this is most likely NOT a supported format. See this link for expected formats.
I would like to add to this and say you should definitely use a parameterised query as suggested by Romoku.

dt1.Month.ToString()
If the month number is 1 digit, and you concatenate, you could end up with a date like this:
2013624 (notice that you need 06, not just 6).
Instead you could try:
(dt1.Year * 10000 + dt1.Month * 100 + dt1.Day).ToString()

You haven't taken into account the need for zero padding on the dates. The code to construct cvt1 and cvt2 should look something like this:
string cvt1 = "'"+dt1.Year.ToString("0000") + dt1.Month.ToString("00") + dt1.Day.ToString("00")+"'";
string cvt2 = "'"+dt2.Year.ToString("0000") + dt2.Month.ToString("00") + dt2.Day.ToString("00")+"'";