Error message is,
Connection must be valid and open.
Is this code wrong? How can i solve the problem?
string strConn = "server = localhost; user = root; database = ****; port = 3306; password = ****; Charset = utf8";
using (MySqlConnection conn = new MySqlConnection(strConn))
{
MySqlCommand insertCommand = new MySqlCommand();
conn.Open();
for (int i = 0; i < 10; i++)
{
insertCommand.CommandText = "INSERT INTO master (col_name, col_code)" +
" SELECT * from (select '" + _name[i] + "', '" + _code[i] + "') as tmp" +
" WHERE NOT EXISTS (" +
" SELECT col_code FROM master WHERE col_code = '" + _name[i] + "') limit 1;";
insertCommand.ExecuteNonQuery();
}
conn.Close();
}
Before your for loop need to set connection for your CommandObject like:
InsertCommand.Connection = conn;
You need to assign the connection to your command by using the connection object you created conn.
MySqlCommand insertCommand = conn.CreateCommand();
So, your code goes like this:
string strConn = "server = localhost; user = root; database = ****; port = 3306; password = ****; Charset = utf8";
using (MySqlConnection conn = new MySqlConnection(strConn))
{
MySqlCommand insertCommand = conn.CreateCommand();
conn.Open();
for (int i = 0; i < 10; i++)
{
insertCommand.CommandText = "INSERT INTO master (col_name, col_code)" +
" SELECT * from (select '" + _name[i] + "', '" + _code[i] + "') as tmp" +
" WHERE NOT EXISTS (" +
" SELECT col_code FROM master WHERE col_code = '" + _name[i] + "') limit 1;";
insertCommand.ExecuteNonQuery();
}
conn.Close(); //you don't need this.
}
No need to close the connection by conn.Close(); because the connection gets automatically closed when the using block is exited.
using (MySqlConnection conn = new MySqlConnection(strConn))
{
//your code
}
Related
I've been working on this function to take a user selected csv file and parse it into an access database. After much trial and error and reading here, the thing will compile and run without crashing but no values are being inserted into the table. This I where I am at currently.
private void openFileDialog1_FileOk(object sender, CancelEventArgs e)
{
productFileName = productOpenDialog.SafeFileName;
productFilePath = Path.GetDirectoryName(productOpenDialog.FileName);
string connectionString = String.Format("Provider = Microsoft.ACE.OLEDB.12.0; Data Source ={0}"+"\\VendorDB.accdb;Persist Security Info = False;", Environment.CurrentDirectory);
string selectSQL = String.Format(#"SELECT * FROM [" + productFileName + "]");
using (OleDbConnection connection = new OleDbConnection(String.Format(#"Provider = Microsoft.ACE.OLEDB.12.0;Data Source={0};Extended Properties=Text;", productFilePath)))
{
using (OleDbCommand command = new OleDbCommand(selectSQL, connection))
{
using (OleDbDataAdapter adapter = new OleDbDataAdapter(command))
{
DataTable dataTable = new DataTable();
adapter.Fill(dataTable);
//create connection to Access DB
OleDbConnection DBconn = new OleDbConnection(connectionString);
OleDbCommand cmd = new OleDbCommand();
//set cmd settings
cmd.Connection = DBconn;
//cmd.CommandType = CommandType.Text;
//open DB connection
DBconn.Open();
//read each row in the Datatable and insert that record into the DB
for (int i = 0; i < dataTable.Rows.Count; i++)
{
cmd.CommandText = "INSERT INTO Product_List (ProductID, ProductName, Description, InventoryItem, Price, CaseSize, SalespersonID)" +
" VALUES ('" + dataTable.Rows[i].ItemArray.GetValue(0) + "','" + dataTable.Rows[i].ItemArray.GetValue(1) + "','" + dataTable.Rows[i].ItemArray.GetValue(2) +
"','" + dataTable.Rows[i].ItemArray.GetValue(3) + "','" + dataTable.Rows[i].ItemArray.GetValue(4) + "','" + dataTable.Rows[i].ItemArray.GetValue(5) +
"','" + dataTable.Rows[i].ItemArray.GetValue(6) + "')";
cmd.ExecuteNonQuery();
}
//close DB.connection
DBconn.Close();
}
}
}
}
I am aware that datatypes in fields might be an issue, so I removed a DateTime and changed price to a short number, so all data is strings and numbers. Despite successfully loading the DataTable from the csv file, no values are inserted into access.
This question already has answers here:
ExecuteNonQuery: Connection property has not been initialized.
(7 answers)
Closed 7 years ago.
I tried to get my sql query read, but it does not really work. It is all working until it comes to the query part and then on the line:
rst = query.ExecuteReader();
It gets an error:
Connection property has not been initialized.
Does anyone know how to handle this?
Chart chart = new Chart();
StringBuilder xmlStr = new StringBuilder();
StringBuilder strCategories = new StringBuilder();
StringBuilder strProcesses = new StringBuilder();
StringBuilder strTasks = new StringBuilder();
xmlStr.Append("<chart logoURL='../../Images/Piktogramme/" + chart.Image + "' caption='" + chart.Caption + "' theme='flat'" + " dateformat='dd/mm/yyyy' showTaskLabels='1'>"); // attributes will go here
// Category for each month
for (int i = -12; i < 6; i++)
{
DateTime today = DateTime.Now;
today = today.AddMonths(i);
strCategories.Append("<category start='1/" + today.Month + "/" + today.Year + "' end='" + DateTime.DaysInMonth(today.Year, today.Month) + "/" + today.Month + "/" + today.Year + "' name='" + today.ToString("MMM") + "' />");
}
// Get the connection string
string connStr = ConfigurationManager.ConnectionStrings["CRM_SQL"].ConnectionString;
using (SqlConnection conn = new SqlConnection(connStr))
{
// Establish the connection with the database
conn.Open();
// Construct and execute SQL query which would return the total amount of sales for each year
SqlCommand query = new SqlCommand();
// Begin iterating through the result set
SqlDataReader rst;
query.CommandText = "SELECT * from table";
rst = query.ExecuteReader();
while (rst.Read())
{
// Construct the chart data in XML format
strProcesses.AppendFormat("<process name='{1}' id='{0}' />", rst[0], rst[1]);
strTasks.AppendFormat("<task name='{0}' processid='{1}' start='{2}' end='{3}' />", rst[4], rst[0], rst[2], rst[3]);
}
DateTime today = DateTime.Now;
xmlStr.Append("<trendlines><line start='" + DateTime.DaysInMonth(today.Year, today.Month) + "/" + today.Month + "/" + today.Year + "' displayvalue='Heute'/></trendlines>");
// End the XML string
xmlStr.Append("<categories>" + strCategories.ToString() + "</categories> <processes>" + strProcesses.ToString() + "</processes> <tasks width='10'>" + strTasks.ToString() + "</tasks> </chart>");
// Close the result set Reader object and the Connection object
rst.Close();
conn.Close();
}
return xmlStr.ToString();
}
Your SqlCommand object has no link to your SqlConnection.
Replace the line:
SqlCommand query = new SqlCommand();
By:
SqlCommand query = conn.CreateCommand();
PS: Like SqlConnection, SqlCommand and SqlDataReader are also disposable, so you can/should also use using.
And the line conn.Close(); is useless because using will take care of it.
One way to do this;
var query = new SqlCommand("SELECT * from table", conn);
another way is assigning the connection string
query.connection = conn;
Add following
query.Connection=conn;
after
SqlCommand query = new SqlCommand();
try this :
using (SqlConnection conn = new SqlConnection(connStr))
{
// Establish the connection with the database
conn.Open();
using (SqlCommand query = new SqlCommand("SELECT * from table", conn))
{
query.CommandType = CommandType.Text;
using (var rst = query.ExecuteReader())
{
while (rst.Read())
{
strProcesses.AppendFormat("<process name='{1}' id='{0}' />", rst[0], rst[1]);
strTasks.AppendFormat("<task name='{0}' processid='{1}' start='{2}' end='{3}' />", rst[4], rst[0], rst[2], rst[3]);
}
}
}
DateTime today = DateTime.Now;
xmlStr.Append("<trendlines><line start='" + DateTime.DaysInMonth(today.Year, today.Month) + "/" + today.Month + "/" + today.Year + "' displayvalue='Heute'/></trendlines>");
// End the XML string
xmlStr.Append("<categories>" + strCategories.ToString() + "</categories> <processes>" + strProcesses.ToString() + "</processes> <tasks width='10'>" + strTasks.ToString() + "</tasks> </chart>");
conn.Close();
}
This probably a simple solution, but I've got a deadline to catch and I don't know the exact problem here.
So here's the deal, I'm trying to update my table using this piece of code:
private void btn_opslaan_Click(object sender, EventArgs e)
{
string opleidingsid = "Select OpleidingsID From opleidingen Where Opleidingsnaam = '" + cb_opleiding.Text + "'";
MySqlCommand cmdid = new MySqlCommand(opleidingsid, dbconnect.connection);
dbconnect.OpenConnection();
MySqlDataReader reader = cmdid.ExecuteReader();
reader.Read();
int oplid = (int)reader.GetValue(0);
cmdid.Dispose();
reader.Close();
sql = "UPDATE leerlingen SET Naam = '_naam', Adres = '_adres', Woonplaats = '_woonplaats', Postcode = '_postcode', Email = '_email', Telefoonnummer = '_telefoonnummer', Klas = '_klas', Ovnummer = '_ovnummer', OpleidingsID = '_opleidingsid', Startdatum = '_startdatum', Einddatum = '_einddatum' WHERE LeerlingID = '_leerlingid'";
// sql = "UPDATE leerlingen set Naam = '" + txt_naam.Text + "', Adres = '" + txt_adres.Text + "', Woonplaats = '" + txt_woonplaats.Text + "', Postcode = '" + txt_postcode.Text + "', Email = '" + txt_email.Text + "', Telefoonnummer = '" + txt_telefoonnumer.Text + "', Klas = '" + txt_klas.Text + "', Ovnummer = '" + txt_ovnummer.Text + "', OpleidingsID = '" + oplID + "', Startdatum = '"+mc_startdatum.SelectionStart.Date.ToString()+"', Einddatum = '"+ mc_einddatum.SelectionStart.Date.ToString() +"' WHERE LeerlingID = '" + Int32.Parse(lbl_leerlingid.Text) + "'";
MySqlCommand cmd = new MySqlCommand(sql, dbconnect.connection);
cmd.Parameters.AddWithValue("_naam", txt_naam.Text);
cmd.Parameters.AddWithValue("_adres", txt_adres.Text);
cmd.Parameters.AddWithValue("_woonplaats", txt_woonplaats.Text);
cmd.Parameters.AddWithValue("_postcode", txt_postcode.Text);
cmd.Parameters.AddWithValue("_email", txt_email.Text);
cmd.Parameters.AddWithValue("_telefoonnummer", txt_telefoonnumer.Text);
cmd.Parameters.AddWithValue("_klas", txt_klas.Text);
cmd.Parameters.AddWithValue("_ovnummer", txt_ovnummer.Text);
cmd.Parameters.AddWithValue("_opleidingsid", oplid);
cmd.Parameters.AddWithValue("_startdatum", mc_startdatum.SelectionStart.Date.ToString());
cmd.Parameters.AddWithValue("_einddatum", mc_einddatum.SelectionStart.Date.ToString());
cmd.Parameters.AddWithValue("_leerlingid", int.Parse(lbl_leerlingid.Text));
try
{
cmd.ExecuteNonQuery();
MessageBox.Show("opslaan gelukt");
}
catch (Exception error)
{
MessageBox.Show(error.ToString());
throw;
}
dbconnect.CloseConnection();
this.Close();
}
I've already tried without the single quotes, it would give me the error that colomn '_leerlingid' does not exist, but that is the parameter...
Now, I dont get any errors, but it wouldn't update my database.
Any help please
P.S. Ignore the sql injection please, before this , i didn't knew better before I found out about parameters.
Try replacing your parameters with the # symbol and remove the single quotes, like this:
SQL = "UPDATE leerlingen SET Naam = #naam, Adres = #adres";
cmd.Parameters.AddWithValue("#naam", txt_naam.Text);
cmd.Parameters.AddWithValue("#adres", txt_adres.Text);
I think what you did wrong is you mustn't initialize your MySqlCommand like that. It must be like this..
MySqlCommand cmd;
cmd = dbconnect.createCommand();
cmd.CommandText = "UPDATE tableName SET firstname=#firstname, lastname=#lastname where id=#id";
cmd.Parameters.AddWithValue("#id", idTxt.Text);
cmd.Parameters.AddWithValue("#firstname", fName.Text);
cmd.Parameters.AddWithValue("#lastname", lName.Text);
cmd.ExecuteNonQuery();
when I creating a new data in c#, I make it like this ..
//values
String a = "COL1ROW1", b = "COL1ROW2";
//this is the code for mysql
String query = "Insert Into tableName(Column1, Column2)values('" + a + "','" + b + "')";
//conn is your mysqlconnection
MySqlCommand cmd = new MySqlCommand(query, conn);
//then execute it
cmd.ExecuteNonQuery();
So I have a table with the following columns:
ID, name, adress, etc..
I have been doing some research but I cannot come across the right keywords to find out to do what I want. I would like to be able to take the name value (Which would be say... "John Doe" which is in the database already for sure..) and retrieve the ID of it (from the int MySQL value ID).
I have come across the following code but I cannot seem to figure out how to extend its limits to match my needs.
connection2.Open();
cmd.ExecuteNonQuery();
try
{
MySqlDataReader myReader = cmd.ExecuteReader();
while (myReader.Read())
{
Console.WriteLine(myReader.GetString(myReader.GetOrdinal("id")));
}
myReader.Close();
}
finally
{
connection2.Close();
}
This is also what I have come up with to the best of my abilities.
MySqlConnection connection2 = new MySqlConnection("Server=" + server + ";" + "Port=" + port + ";" + "Database=" + database + ";" + "Uid=" + uid + ";" + "Password=" + password + ";");
string query = #"SELECT id FROM caregiverdatabse WHERE name Like '%" + caregiverNameDisp.Text + "%'";
MySqlCommand cmd = new MySqlCommand(query, connection2);
You should replace the hard coded parameters with sql parameters, but here is a general idea of what you'll need to do here. Using your present sql query.
MySqlConnection sqlConn = new MySqlConnection();
MySqlCommand sqlCmd = new MySqlCommand();
string sSql = "SELECT id FROM caregiverdatabse WHERE name Like '%" + caregiverNameDisp.Text + "%'";
sqlConn.ConnectionString = "Server=" + server + ";" + "Port=" + port + ";" + "Database=" + database + ";" + "Uid=" + uid + ";" + "Password=" + password + ";";
sqlCmd.CommandText = sSql;
sqlCmd.CommandType = CommandType.Text;
sqlConn.Open();
sqlCmd.Connection = sqlConn;
MySqlDataReader reader = sqlCmd.ExecuteReader();
List<string> results = new List<string>();
while (reader.Read())
{
results.Add((reader["id"].ToString());
}
reader.Close();
sqlConn.Close();
Keep in mind you can add the reader results to a string, to a list like above, whatever you want to do with it.
this how id en name pawe
clsMySQL.sql_con.Open();
string id = ID;
sql = "SELECT *FROM test";
cmd = new MySqlCommand(sql, clsMySQL.sql_con);
sql_cmd = new MySqlCommand(sql, clsMySQL.sql_con);
MySqlDataReader dr = cmd.ExecuteReader();
if (dr.Read())
{
id = dr["id"].ToString();
user = dr["user_name"].ToString();
pass = dr["password"].ToString();
if (name.Text == user && passw.Text == pass)
{
string depart = id;
Hide();
MessageBox.Show("it works");
// Then show the main form
cracker form = new cracker(name.Text);
form.sid = depart;
form.Show();
MessageBox.Show(ID);
}
}
else
{
MessageBox.Show("Invalid Login please check username and password");
}
clsMySQL.sql_con.Close();
}
I'm running Windows 7 and II7 and SQL server 2008 R2 . I have an aspx program and when I try to run it I get the following error
Parameters supplied for object 'users' which is not a function. If
the parameters are intended as a table hint, a WITH keyword is
required.
What I've coded is this :
public ArrayList GetGoodsList(string type, string goodsType, string user, string payType, bool flag)
{
conn = new SqlConnection(System.Configuration.ConfigurationManager.AppSettings["Conn"].ToString());
DataSet ds = new DataSet();
sSql = "select count(*) from users('" + type + "','" + goodsType + "','" + user + "','" + payType + "')";
if (flag == true)
{
sSql += "where IsCommend = 1";
}
SqlCommand cmd = new SqlCommand();
cmd.Connection = conn;
cmd.CommandText = sSql;
conn.Open();
int maxRow = Int32.Parse(cmd.ExecuteScalar().ToString());
sSql = "select * from users('" + type + "','" + goodsType + "','" + user + "','" + payType + "')";
if (flag == true)
{
sSql += "where IsCommend = 1";
}
cmd.CommandText = sSql;
SqlDataReader reader = cmd.ExecuteReader();
ArrayList gInfos = new ArrayList();
GoodsInfo gInfo;
for (int i = 0; i < maxRow; i++)
{
if (reader.Read())
{
gInfo = new GoodsInfo();
gInfo.G_ID = Int32.Parse(reader["G_ID"].ToString());
gInfo.G_Name = reader["G_Name"].ToString();
gInfo.Type = reader["Type"].ToString();
gInfo.GoodsType = reader["GoodsType"].ToString();
gInfos.Add(gInfo);
}
}
conn.Close();
return gInfos;
}
Any idea? Thanks!
Without giving away the answer, your issue in in your SELECT statement, sSql = ...
It's not the correct SQL syntax.
Have a read of this wikipedia article on the SELECT statement.