Develop Reference

C# Insert Record into Database table

I have a database that contains a Customer table with the following columns : CustID, CustName, ICNumber, ContactNumber and Address. It is a service-based database.
string localdb = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
SqlConnection con = new SqlConnection(localdb);
con.Open();
SqlCommand cmd = new SqlCommand("INSERT INTO Customer(CustID,CustName,ICNumber,ContactNumber,Address)values(#CustID,#CustName,#ICNumber,#ContactNumber,#Address)", con);
cmd.Parameters.AddWithValue("#CustID", txtCustID.Text);
cmd.Parameters.AddWithValue("#CustName", txtCustName.Text);
cmd.Parameters.AddWithValue("#ICNumber", txtICNum.Text);
cmd.Parameters.AddWithValue("#ContactNumber", txtContact.Text);
cmd.Parameters.AddWithValue("#Address", txtAddress.Text);
cmd.ExecuteNonQuery();
con.Close();
The code compiles and runs. The problem I am having is that the record is not added into the table after cmd.ExecuteNonQuery(); is called.
Why is the record not showing up in the database table?

You forgot to close the quotes " on the insert command. It is nice to use try/catch to avoid problems with your insert, for sample:
string localdb = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
try
{
SqlConnection con = new SqlConnection(localdb))
con.Open();
SqlCommand cmd = new SqlCommand("INSERT INTO Customer(CustID, CustName, ICNumber, ContactNumber, Address) VALUES (#CustID, #CustName, #ICNumber, #ContactNumber, #Address)", con);
cmd.Parameters.AddWithValue("#CustID", txtCustID.Text);
cmd.Parameters.AddWithValue("#CustName", txtCustName.Text);
cmd.Parameters.AddWithValue("#ICNumber", txtICNum.Text);
cmd.Parameters.AddWithValue("#ContactNumber", txtContact.Text);
cmd.Parameters.AddWithValue("#Address", txtAddress.Text);
cmd.ExecuteNonQuery();
}
catch
{
// some errors
}
finally
{
if (con.State == ConnectionState.Open)
con.Close();
}

Syntax error in INSERT INTO statement with parameters

i am getting this error so often, i can't find out what's wrong in here?
con.Open();
String query = "INSERT INTO user (username,[password]) values(a,b)";
OleDbCommand cmd1 = new OleDbCommand(query, con);
cmd1.Parameters.AddWithValue("a",textBox1.Text);
cmd1.Parameters.AddWithValue("b", textBox2.Text);
cmd1.ExecuteNonQuery();
con.Close();
MessageBox.Show("User Account Created");
this.Close();

SqlParameters should start with # like #Name. try this:
con.Open();
String query = "INSERT INTO user (Username, [Password]) values(#Username, #Password)";
OleDbCommand cmd = new OleDbCommand(query, con);
cmd.Parameters.AddWithValue("#Username",textBox1.Text);
cmd.Parameters.AddWithValue("#Password", textBox2.Text);
cmd.ExecuteNonQuery();
con.Close();
MessageBox.Show("User Account Created");
this.Close();
Read Using Variables and Parameters

Why is this insert not working?`

Actually my code was suppose to check that is there any value in the course_choice_teacher table. If there is not, then it will insert some values into the table. Now this time there is no value in the table. So dr2.Read() should return false and do the else portion. But it is doing the reverse thing. I'll be very happy if you help me in this purpose.
string oradb = "Data Source=localhost;User Id=system;Password=cse;";
OracleConnection conn = new OracleConnection(oradb); // C#
conn.Open();
OracleCommand cmd2 = new OracleCommand();
cmd2.Connection = conn;
cmd2.CommandText = "select * from course_choice_teacher where teacher_id='"+teacher_home.st+"' and choice_no=1";
cmd2.CommandType = CommandType.Text;
OracleDataReader dr2 = cmd2.ExecuteReader();
if (dr2.Read())
{
MessageBox.Show("Already Given");
}
else
{
OracleCommand cmd = new OracleCommand();
cmd.Connection = conn;
cmd.CommandText = "insert into course_choice_teacher values('" + teacher_home.st + "','" + dataGridView1.CurrentRow.Cells["course_id"].Value.ToString() + "',1)";
cmd.CommandType = CommandType.Text;
OracleDataReader dr = cmd.ExecuteReader();
dr.Read();
}
conn.Dispose();

The datareader has property .HasRows to check if the result has some rows. This would be a proper way to check what you intend to do.
if (dr2.HasRows)
{
MessageBox.Show("Already Given");
}
else
{
.........
}

C# Get insert id with Auto Increment

I am using this method to insert a row into a table:
MySqlConnection connect = new MySqlConnection(connectionStringMySql);
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = connect;
cmd.Connection.Open();
string commandLine = #"INSERT INTO Wanted (clientid,userid,startdate,enddate) VALUES" +
"(#clientid, #userid, #startdate, #enddate);";
cmd.CommandText = commandLine;
cmd.Parameters.AddWithValue("#clientid", userId);
cmd.Parameters.AddWithValue("#userid", "");
cmd.Parameters.AddWithValue("#startdate", start);
cmd.Parameters.AddWithValue("#enddate", end);
cmd.ExecuteNonQuery();
cmd.Connection.Close();
I hav also id column that have Auto Increment .
And i want to know if it possible to get the id that is created when i insert a new row.

You can access the MySqlCommand LastInsertedId property.
cmd.ExecuteNonQuery();
long id = cmd.LastInsertedId;

MySqlConnection connect = new MySqlConnection(connectionStringMySql);
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = connect;
cmd.Connection.Open();
string commandLine = #"INSERT INTO Wanted (clientid,userid,startdate,enddate) "
+ "VALUES(#clientid, #userid, #startdate, #enddate);";
cmd.CommandText = commandLine;
cmd.Parameters.AddWithValue("#clientid", userId);
**cmd.Parameters["#clientid"].Direction = ParameterDirection.Output;**
cmd.Parameters.AddWithValue("#userid", "");
cmd.Parameters.AddWithValue("#startdate", start);
cmd.Parameters.AddWithValue("#enddate", end);
cmd.ExecuteNonQuery();
cmd.Connection.Close();

Basically you should add this to end of your CommandText:
SET #newPK = LAST_INSERT_ID();
and add another ADO.NET parameter "newPK". After command is executed it will contain new ID.

Oledb Update command

I make a program that saves and update a data from the database, I can save and read data, I can also update but the problem is, I can't select the "ID" as the index, here is my sample code using "ID" as the index,
cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE Records SET FirstName = #firstname, LastName = #lastname, Age = #age, Address = #address, Course = #course WHERE [ID] = #id";
cmd.Parameters.AddWithValue("#id", int.Parse(label7.Text));
cmd.Parameters.AddWithValue("#firstname", textBox1.Text);
cmd.Parameters.AddWithValue("#lastname", textBox2.Text);
cmd.Parameters.AddWithValue("#age", textBox3.Text);
cmd.Parameters.AddWithValue("#address", textBox4.Text);
cmd.Parameters.AddWithValue("#course", textBox5.Text);
cmd.Connection = cn;
cn.Open();
cmd.ExecuteNonQuery();
{
MessageBox.Show("Update Success!");
cn.Close();
}
and here is my update code that works, but the index is the "firstname",
cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE Records SET FirstName = #firstname, LastName = #lastname, Age = #age, Address = #address, Course = #course WHERE FirstName = #firstname";
//cmd.Parameters.AddWithValue("#id", int.Parse(label7.Text));
cmd.Parameters.AddWithValue("#firstname", textBox1.Text);
cmd.Parameters.AddWithValue("#lastname", textBox2.Text);
cmd.Parameters.AddWithValue("#age", textBox3.Text);
cmd.Parameters.AddWithValue("#address", textBox4.Text);
cmd.Parameters.AddWithValue("#course", textBox5.Text);
cmd.Connection = cn;
cn.Open();
cmd.ExecuteNonQuery();
{
MessageBox.Show("Update Success!");
cn.Close();`
}
It works but the problem is I can't update the "FirstName", Is there a way that I can also update the Firstname? or use the "ID" as the index? thanks

I don't know what database you are going against, however, I don't know if the OleDB is being picky on the ordinal sequence of your parameters. ie: Have you tried putting your "ID" parameter in the last position to match the actual order of the fields of your update command? I don't know if it's throwing it out.

You should add the following code after the last line of ID:
cmd = new OleDbCommand();
cmd.CommandType = CommandType.Text;
cmd.CommandText = "UPDATE Records SET FirstName = #firstname, LastName = #lastname, Age = #age, Address = #address, Course = #course WHERE [ID] = #id";
cmd.Parameters.AddWithValue("#firstname", textBox1.Text);
cmd.Parameters.AddWithValue("#lastname", textBox2.Text);
cmd.Parameters.AddWithValue("#age", textBox3.Text);
cmd.Parameters.AddWithValue("#address", textBox4.Text);
cmd.Parameters.AddWithValue("#course", textBox5.Text);
cmd.Parameters.AddWithValue("#id", int.Parse(label7.Text));
cmd.Connection = cn;
cn.Open();
cmd.ExecuteNonQuery(); {
MessageBox.Show("Update Success!");
cn.Close();
}