SQL Insert Query Using C#

Question

I'm having an issue at the moment which I am trying to fix. I just tried to access a database and insert some values with the help of C#

The things I tried (worked)

String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES ('abc',      'abc', 'abc', 'abc')";

A new line was inserted and everything worked fine, now I tried to insert a row using variables:

String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id, @username, @password, @email)";

command.Parameters.AddWithValue("@id","abc")
command.Parameters.AddWithValue("@username","abc")
command.Parameters.AddWithValue("@password","abc")
command.Parameters.AddWithValue("@email","abc")

command.ExecuteNonQuery();

Didn't work, no values were inserted. I tried one more thing

command.Parameters.AddWithValue("@id", SqlDbType.NChar);
command.Parameters["@id"].Value = "abc";

command.Parameters.AddWithValue("@username", SqlDbType.NChar);
command.Parameters["@username"].Value = "abc";

command.Parameters.AddWithValue("@password", SqlDbType.NChar);
command.Parameters["@password"].Value = "abc";

command.Parameters.AddWithValue("@email", SqlDbType.NChar);
command.Parameters["@email"].Value = "abc";

command.ExecuteNonQuery();

May anyone tell me what I am doing wrong?

Kind regards

EDIT:

in one other line I was creating a new SQL-Command

var cmd = new SqlCommand(query, connection);

Still not working and I can't find anything wrong in the code above.

Meteorology

Where are you setting command.CommandText? – Warram

Have you tried adding your parameters (in the Parameters.Add) without the @? E.g. command.Parameters.AddWithValue("id","abc") – Tasimeter

^ he's saying you need command.CommandText = query otherwise your query isn't associated with command at all – Denotative

You said @password - but you meant @saltedPasswordHash, right? ;p – Karmakarmadharaya

What is your error message from DB? IMHO U have primary unique key and row with this value is already set. Sou try change id for another string than 'abc' – Exterminatory

I've edited the original entry. I am creating a new command and adding the query into it, should work this way as well I suppose. – Meteorology

Answer 1

I assume you have a connection to your database and you can not do the insert parameters using c #.

You are not adding the parameters in your query. It should look like:

String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username,@password, @email)";

SqlCommand command = new SqlCommand(query, db.Connection);
command.Parameters.Add("@id","abc");
command.Parameters.Add("@username","abc");
command.Parameters.Add("@password","abc");
command.Parameters.Add("@email","abc");

command.ExecuteNonQuery();

Updated:

using(SqlConnection connection = new SqlConnection(_connectionString))
{
    String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username,@password, @email)";

    using(SqlCommand command = new SqlCommand(query, connection))
    {
        command.Parameters.AddWithValue("@id", "abc");
        command.Parameters.AddWithValue("@username", "abc");
        command.Parameters.AddWithValue("@password", "abc");
        command.Parameters.AddWithValue("@email", "abc");

        connection.Open();
        int result = command.ExecuteNonQuery();

        // Check Error
        if(result < 0)
            Console.WriteLine("Error inserting data into Database!");
    }
}

Bergschrund

Please note the overload of Add() shown here has been deprecated for a while. – Nonstriated

Link documenting the deprecation: msdn.microsoft.com/en-us/library/9dd8zze1(v=vs.110).aspx – Nonstriated

you need to open a connection before ExecuteNonQuery – Slopwork

If Add() is deprecated, then what's the new way to insert? – Aalii

MSDN documentation re: deprecated Add() replacement: google.de/… – Oppressive

Add() is deprecated, Try AddWithValue – Southernmost

Its best practice to put the SqlCommand (and the SqlConnection) in a "using" statement. – Aquarius

Note for those reading these comments: Only Add(parameterName, value) is deprecated. The Add(parameterName, sqlDbType) and similar methods that specify the data type are perfectly fine and not going anywhere. For example, you can still use command.Parameters.Add("@username",SqlDbType.NChar).Value = "abc". What's deprecated is not specifying the parameter's data type. – Lilianaliliane

Answer 2

Try

String query = "INSERT INTO dbo.SMS_PW (id,username,password,email) VALUES (@id,@username, @password, @email)";
using(SqlConnection connection = new SqlConnection(connectionString))
using(SqlCommand command = new SqlCommand(query, connection))
{
    //a shorter syntax to adding parameters
    command.Parameters.Add("@id", SqlDbType.NChar).Value = "abc";

    command.Parameters.Add("@username", SqlDbType.NChar).Value = "abc";

    //a longer syntax for adding parameters
    command.Parameters.Add("@password", SqlDbType.NChar).Value = "abc";

    command.Parameters.Add("@email", SqlDbType.NChar).Value = "abc";

    //make sure you open and close(after executing) the connection
    connection.Open();
    command.ExecuteNonQuery();
}

Captor

I am already using the exact same code. I am opening a connection, creating a SQLCommand with the query and the connection and executing the same steps. No clue why it is not working – Meteorology

I'm sorry, didn't see that you used the Add method. It did work now. I have no clue why this is the only way but I am glad that it does finally work. Thanks so much – Meteorology

There is no need to call connection.Close() if your SqlConnection object is in using block, Dispose() will do that for you. – Apnea

Answer 3

The most common mistake (especially when using express) to the "my insert didn't happen" is : looking in the wrong file.

If you are using file-based express (rather than strongly attached), then the file in your project folder (say, c:\dev\myproject\mydb.mbd) is not the file that is used in your program. When you build, that file is copied - for example to c:\dev\myproject\bin\debug\mydb.mbd; your program executes in the context of c:\dev\myproject\bin\debug\, and so it is here that you need to look to see if the edit actually happened. To check for sure: query for the data inside the application (after inserting it).

Karmakarmadharaya

OP says non parameterized query works fine. Since abc has already been inserted for username, database may not allow abc again if there is a unique key constraint set up for username. – Protractor

@Protractor hmmm; interesting - but you would expect a unique constraint violation as an exception in that case – Karmakarmadharaya

Answer 4

static SqlConnection myConnection;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        myConnection = new SqlConnection("server=localhost;" +
                                                      "Trusted_Connection=true;" +
             "database=zxc; " +
                                                      "connection timeout=30");
        try
        {

            myConnection.Open();
            label1.Text = "connect successful";

        }
        catch (SqlException ex)
        {
            label1.Text = "connect fail";
            MessageBox.Show(ex.Message);
        }
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void button2_Click(object sender, EventArgs e)
    {
        String st = "INSERT INTO supplier(supplier_id, supplier_name)VALUES(" + textBox1.Text + ", " + textBox2.Text + ")";
        SqlCommand sqlcom = new SqlCommand(st, myConnection);
        try
        {
            sqlcom.ExecuteNonQuery();
            MessageBox.Show("insert successful");
        }
        catch (SqlException ex)
        {
            MessageBox.Show(ex.Message);
        }
    }

Bidentate

Answer 5

private void button1_Click(object sender, EventArgs e)
    {
        String query = "INSERT INTO product (productid, productname,productdesc,productqty) VALUES (@txtitemid,@txtitemname,@txtitemdesc,@txtitemqty)";
        try
        {
            using (SqlCommand command = new SqlCommand(query, con))
            {

                command.Parameters.AddWithValue("@txtitemid", txtitemid.Text);
                command.Parameters.AddWithValue("@txtitemname", txtitemname.Text);
                command.Parameters.AddWithValue("@txtitemdesc", txtitemdesc.Text);
                command.Parameters.AddWithValue("@txtitemqty", txtitemqty.Text);


                con.Open();
                int result = command.ExecuteNonQuery();

                // Check Error
                if (result < 0)
                    MessageBox.Show("Error");

                MessageBox.Show("Record...!", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
                con.Close();
                loader();
            }
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
            con.Close();
        }
    }

Hydrotherapy

Answer 6

public static string textDataSource = "Data Source=localhost;Initial 
Catalog=TEST_C;User ID=sa;Password=P@ssw0rd";
public static bool ExtSql(string sql) {
    SqlConnection cnn;
    SqlCommand cmd;
    cnn = new SqlConnection(textDataSource);
    cmd = new SqlCommand(sql, cnn);
    try {
        cnn.Open();
        cmd.ExecuteNonQuery();
        cnn.Close();
        return true;
    }
    catch (Exception) {
        return false;
    }
    finally {
        cmd.Dispose();
        cnn = null;
        cmd = null; 
    }
}

Disseminule

Answer 7

I have just wrote a reusable method for that, there is no answer here with reusable method so why not to share...
here is the code from my current project:

public static int ParametersCommand(string query,List<SqlParameter> parameters)
{
    SqlConnection connection = new SqlConnection(ConnectionString);
    try
    {
        using (SqlCommand cmd = new SqlCommand(query, connection))
        {   // for cases where no parameters needed
            if (parameters != null)
            {
                cmd.Parameters.AddRange(parameters.ToArray());
            }

            connection.Open();
            int result = cmd.ExecuteNonQuery();
            return result;
        }
    }
    catch (Exception ex)
    {
        AddEventToEventLogTable("ERROR in DAL.DataBase.ParametersCommand() method: " + ex.Message, 1);
        return 0;
        throw;
    }

    finally
    {
        CloseConnection(ref connection);
    }
}

private static void CloseConnection(ref SqlConnection conn)
{
    if (conn.State != ConnectionState.Closed)
    {
        conn.Close();
        conn.Dispose();
    }
}

Ka

Answer 8

class Program
{
    static void Main(string[] args)
    {
        string connetionString = null;
        SqlConnection connection;
        SqlCommand command;
        string sql = null;

        connetionString = "Data Source=Server Name;Initial Catalog=DataBaseName;User ID=UserID;Password=Password";
        sql = "INSERT INTO LoanRequest(idLoanRequest,RequestDate,Pickupdate,ReturnDate,EventDescription,LocationOfEvent,ApprovalComments,Quantity,Approved,EquipmentAvailable,ModifyRequest,Equipment,Requester)VALUES('5','2016-1-1','2016-2-2','2016-3-3','DescP','Loca1','Appcoment','2','true','true','true','4','5')";
        connection = new SqlConnection(connetionString);

        try
        {
            connection.Open();
            Console.WriteLine(" Connection Opened ");
            command = new SqlCommand(sql, connection);                
            SqlDataReader dr1 = command.ExecuteReader();         

            connection.Close();
        }
        catch (Exception ex)
        {
            Console.WriteLine("Can not open connection ! ");
        }
    }
}

Threedimensional

For Inserting you don't need to use execute reader , instead of reader we should use ExecuteNonquery for insert , update and delete to verify the affected rows.. Using block and parameterized queries are explained by the @theLaw.. parameterized queries is very effective in case of sql injections and if we use Using Block we don't need to bother about closing connections.. – Loam