I have tried MANY suggested solutions from here but nothing seems to work for this problem. I just keep getting this error message when it hits the 'mdr = command.ExecuteReader();' line. Any thoughts please?
try
{
MySqlConnection connection = new MySqlConnection("SERVER=" + server + ";" + "DATABASE=" + database + ";" + "UID=" + uid + ";" + "PASSWORD=" + password + ";");
MySqlCommand command;
MySqlDataReader mdr;
connection.Open();
string ThePID = tbPID.Text;
string TheRound = tbRound.Text;
string CurrentPage = tbCurrentPage.Text;
// SELECT #myvar:= myvalue
string query = "SELECT ImageURL, ProofingText " +
"INTO #ImageURL, #ProofingText " +
"FROM Rounds " +
"WHERE ProjectID = " + ThePID + " " +
"AND CurrentRound = " + TheRound + " " +
"AND Page = " + CurrentPage + ";";
command = new MySqlCommand(query, connection);
mdr = command.ExecuteReader();
mdr.Read();
rtProofing.Text = mdr.GetString("#PRoofingText");
tbURL.Text = mdr.GetString("#ImageURL");
tbImagePage.Text = Path.GetFileName(tbURL.Text);
PageBox.Image = Image.FromFile(tbURL.Text);
connection.Close();
connection.Dispose();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
If you use MySqlConnector, you will get a helpful exception message that explains the problem:
Parameter '#ImageURL' must be defined. To use this as a variable, set 'Allow User Variables=true' in the connection string.
By default, MySQL queries (executed from .NET) can't use user-defined variables. You can relax this limitation by adding Allow User Variables=true to your connection string.
However, this won't fix your underlying problem, which is that this isn't the right way to select data from MySQL.
Firstly, your query is susceptible to SQL injection; you should rewrite it to use parameters as follows:
using (var command = connection.CreateCommand())
{
command.CommandText = #"SELECT ImageURL, ProofingText
FROM Rounds
WHERE ProjectID = #ThePID
AND CurrentRound = #TheRound
AND Page = #CurrentPage;";
commands.Parameters.AddWithValue("#ThePID", ThePID);
commands.Parameters.AddWithValue("#TheRound", TheRound);
commands.Parameters.AddWithValue("#CurrentPage", CurrentPage);
Then, you can retrieve the values with a slight variation on your current code. You must retrieve the values by their column names, which do not have a leading #. You should also check that a row was retrieved by examining the return value of Read():
if (mdr.Read())
{
rtProofing.Text = mdr.GetString("ProofingText");
tbURL.Text = mdr.GetString("ImageURL");
}
Finally, string concatenation is also not the right way to build a connection string. The MySqlConnectionStringBuilder class exists for this purpose; use it.
var builder = new MySqlConnectionStringBuilder
{
Server = server,
Database = database,
UserID = uid,
Password = password,
};
using var connection = new MySqlConnection(csb.ConnectionString);
Related
Building a tool to backup a database that I'm testing locally first. I'm trying to check if compression is supported and change my SQL query based on the value returned. Running it against an actual live server returns 0 or 1, but running the query itself against a local instance doesn't give a value. As a result I don't believe the if statements ever run to change the CommandText and my final WriteLine test returns the initial compression query instead of one of the backup commands.
I tried changing the if to check for a null, however the else should catch any other values besides '1'
string compressionQuery = "SELECT VALUE FROM sys.configurations WHERE name = 'backup compression default'";
SqlCommand sqlCmd = new SqlCommand(compressionQuery, newConn);
SqlDataReader reader = sqlCmd.ExecuteReader();
while (reader.Read()) //while the data reader is checking the records
{
Interface.WriteLine(reader.GetInt32(0).ToString()); //print the specified record(row) to the console
canCompress = reader.GetInt32(0);
// Backup the database.
if (canCompress == 1)
{
sqlCmd.CommandText = "BACKUP DATABASE [" + connBuilder.InitialCatalog + "] "
+ "TO DISK = '" + backupPath + "' "
+ "WITH COPY_ONLY, COMPRESSION, NOFORMAT, NOINIT, "
+ "NAME = '" + backupName + "', "
+ "SKIP, REWIND, NOUNLOAD, STATS = 10";
Interface.WriteLine("1");
}
else
{
sqlCmd.CommandText = "BACKUP DATABASE [" + connBuilder.InitialCatalog + "] "
+ "TO DISK = '" + backupPath + "' "
+ "WITH COPY_ONLY, NOFORMAT, NOINIT, "
+ "NAME = '" + backupName + "', "
+ "SKIP, REWIND, NOUNLOAD, STATS = 10";
Interface.WriteLine("0");
}
}
reader.Close(); //stop reading records
Interface.WriteLine(sqlCmd.CommandText.ToString()); //Should print one of the backup queries
sqlCmd.ExecuteNonQuery();
It should return one of the nested backup commands. Right now it simply writes the initial compression query.
Backup compression is not available in all editions of SQL Server. So in my sqlexpress the value is not even in the table, it is probably your case too. reader.Read() never reads anything, so you do not get into the if part at all. You can restructuralize you code
bool canCompress = false;
using (SqlDataReader reader = sqlCmd.ExecuteReader())
{
while (reader.Read())
{
canCompress = reader.GetInt32(0) == 1;
}
}
if (canCompress)
{
...
}
else
{
...
}
And you can even simplify the reading like this
bool canCompress = (int?)sqlCmd.ExecuteScalar() == 1;
The following code gets a value which indicates whether backup compression is supported and, if so, whether it is enabled by default.
using (SqlConnection dbConnection = new SqlConnection("Your connection string.")
{
dbConnection.Open();
using (SqlCommand dbCommand = new SqlCommand(
"select value from sys.configurations where name = 'backup compression default';", dbConnection))
{
// The values are:
// null Backup compression is not supported.
// 0 Backup compression is supported and disabled by default.
// 1 Backup compression is supported and enabled by default.
int? backupCompressionDefault = (int?)dbCommand.ExecuteScalar();
}
dbConnection.Close();
}
Note that the value column in sys.configurations is declared as sql_variant. The actual type returned can be displayed thusly:
select SQL_VARIANT_PROPERTY( value, 'basetype' )
from sys.configurations
where name = 'backup compression default';
I am trying to update database records over a range in Access using SQL and C#. Using an UPDATE query keeps giving me an error
Syntax error (missing operator) in query expression
All of the query criteria is from user input. I have tried a number of sources to find an answer but I believe my SQL statement is correct. Below is the method that is performing the task that I need.
private void btnUpdate_Click(object sender, EventArgs e)
{
int teamYear = Convert.ToInt32(this.textBoxBegYear.Text);
int endYear = Convert.ToInt32(this.textBoxEndYear.Text);
string teamName = this.textBoxTeamName.Text;
string league = this.textBoxLeague.Text;
string conference = this.textBoxConf.Text;
string division = this.textBoxDivision.Text;
try
{
dbConn = new OleDbConnection();
dbConn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source="
+ ch + openFileDialog1.FileName + ch;
dbConn.Open();
sql = "UPDATE " + this.comboBox1.SelectedItem.ToString()
+ " SET LeagueName = #leagueName, ConferenceName = #conferenceName,
DivisionName = #divisionName WHERE TeamName = " + this.textBoxTeamName.Text
+ " AND TeamYear BETWEEN " + this.textBoxBegYear.Text
+ " AND " + this.textBoxEndYear.Text;
dbCmd = new OleDbCommand(sql, dbConn);
for (int i = teamYear; i <= endYear; i++)
{
dbCmd.Parameters.AddWithValue("#leagueName", league);
dbCmd.Parameters.AddWithValue("#conferenceName", conference);
dbCmd.Parameters.AddWithValue("#divisionName", division);
dbCmd.ExecuteNonQuery();
}
dbCmd.Connection.Close();
dbConn.Close();
}
catch (Exception err)
{
MessageBox.Show("Error: " + err.Message.ToString());
}
}
The exception comes from the second half of the SQL statement after the WHERE clause asking for a missing operator.
Can anyone happen to see what I may be missing? Any help would be appreciated.
Why don't you replace the code in the "try" block to this:
dbConn = new OleDbConnection();
dbConn.ConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source="
+ ch + openFileDialog1.FileName + ch;
dbConn.Open();
sql = "UPDATE " + this.comboBox1.SelectedItem.ToString()
+ " SET LeagueName = #leagueName, ConferenceName = #conferenceName,
DivisionName = #divisionName WHERE TeamName = #teamName AND TeamYear BETWEEN #begYear AND #endYear";
dbCmd = new OleDbCommand(sql, dbConn);
for (int i = teamYear; i <= endYear; i++)
{
dbCmd.Parameters.AddWithValue("#leagueName", league);
dbCmd.Parameters.AddWithValue("#conferenceName", conference);
dbCmd.Parameters.AddWithValue("#divisionName", division);
dbCmd.Parameters.AddWithValue("#teamName", this.textBoxTeamName.Text);
dbCmd.Parameters.AddWithValue("#begYear", int.Parse(this.textBoxBegYear.Text));
dbCmd.Parameters.AddWithValue("#endYear", int.Parse(this.textBoxBegYear.Text));
dbCmd.ExecuteNonQuery();
}
dbCmd.Connection.Close();
dbConn.Close();
Therefore, you have better idea what the SQL query looks like, and you parameterize users' input to improve security (prevent any sql injection).
To troubleshoot your issue, you may need to debug into this piece of code and see what's the SQL query is, and try to execute it from your SQL client tool (such as Sql management studio), you will have better idea what goes wrong.
Hope this helps.
Henry Liang
You might be missing single quotes '...
TeamName = '" + this.textBoxTeamName.Text + "'
Also, I'm assuming this is just a project you're playing around with and nothing that will be available online? Reason I ask is that the SQL query is vulnerable to SQL injection attacks.
You need to escape the text from the user input with single quotes.
WHERE TeamName = '" + this.textBoxTeamName.Text
+ "' AND TeamYear BETWEEN " + this.textBoxBegYear.Text
+ " AND " + this.textBoxEndYear.Text;
(Notice the single quotes).
Please do not use the code you posted. Please read up on SQL Injection attacks and why your code is very unsafe and replace it with some properly cleaned input handling.
I've been googling/reading for hours and just coming up more and more frustrated.
Here's my code
NpgsqlConnection conn = new NpgsqlConnection("Server=" + Properties.Settings.Default.db_server + ";Port=" + Properties.Settings.Default.db_port + ";User Id=" + Properties.Settings.Default.db_user + ";Password=" + Properties.Settings.Default.db_password + ";Database=" + Properties.Settings.Default.db_database + ";");
conn.Open();
NpgsqlCommand command = new NpgsqlCommand("SELECT user_password FROM users WHERE user_initials = :value1", conn);
// Now add the parameter to the parameter collection of the command specifying its type.
command.Parameters.Add(new NpgsqlParameter("value1", NpgsqlTypes.NpgsqlDbType.Char));
// Now, add a value to it and later execute the command as usual.
command.Parameters[0].Value = initials.Text;
string userPass;
try
{
userPass = (string)command.ExecuteScalar();
MessageBox.Show(userPass);
}
finally
{
conn.Close();
}
With a valid value in the text of initials it's only returning a blank result. if I hard code the initials I get a result with text.
i was trying to update two tables at once, but i got some syntax error on update code could u give me some idea? the insert code works perfect and i tried to copy the insert code and edit on update button clicked
here is my code
private void button2_Click(object sender, EventArgs e)
{
System.Data.OleDb.OleDbConnection conn = new System.Data.OleDb.OleDbConnection();
conn.ConnectionString = #"Provider=Microsoft.ACE.OLEDB.12.0;" +
#"Data source= C:\Users\user\Documents\Visual Studio 2010\Projects\WindowsFormsApplication1\WindowsFormsApplication1\crt_db.accdb";
try
{
conn.Open();
String Name = txtName.Text.ToString();
String AR = txtAr.Text.ToString();
String Wereda = txtWereda.Text.ToString();
String Kebele = txtKebele.Text.ToString();
String House_No = txtHouse.Text.ToString();
String P_O_BOX = txtPobox.Text.ToString();
String Tel = txtTel.Text.ToString();
String Fax = txtFax.Text.ToString();
String Email = txtEmail.Text.ToString();
String Item = txtItem.Text.ToString();
String Dep = txtDep.Text.ToString();
String k = "not renwed";
String Remark = txtRemark.Text.ToString();
String Type = txtType.Text.ToString();
String Brand = txtBrand.Text.ToString();
String License_No = txtlicense.Text.ToString();
String Date_issued = txtDate.Text.ToString();
String my_querry = "update crtPro set Name='" + Name + "',AR='" + AR + "',Wereda='" + Wereda + "',Kebele='" + Kebele + "',House_No='" + House_No + "',P_O_BOX='" + P_O_BOX + "',Tel='" + Tel + "',Fax='" + Fax + "',Email='" + Email + "',Item='" + Item + "',Dep='" + Dep + "','" + k + "',Remark='" + Remark + "' where Name='" + Name + "' ";
OleDbCommand cmd = new OleDbCommand(my_querry, conn);
cmd.ExecuteNonQuery();
String my_querry1 = "SELECT max(PID) FROM crtPro";
OleDbCommand cmd1 = new OleDbCommand(my_querry1, conn);
string var = cmd1.ExecuteScalar().ToString();
String ki = txtStatus.Text.ToString();
String my_querry2 = "update crtItemLicense set PID=" + var + ",Type='" + Type + "',Brand='" + Brand + "',License_No='" + License_No + "',Date_issued='" + Date_issued + "' where PID=" + var + "";
OleDbCommand cmd2 = new OleDbCommand(my_querry2, conn);
cmd2.ExecuteNonQuery();
MessageBox.Show("Message added succesfully");
}
catch (Exception ex)
{
MessageBox.Show("Failed due to" + ex.Message);
}
finally
{
conn.Close();
}
The most likely problem based on the little information given (what database are you using for example - SQL Server 2012?), is that the datatype you are providing in the concatenated dynamic sql does not match the datatype of the column in the database. You've surrounded each value with quotes - which means it will be interpreted as a varchar. If you've got a date value in the wrong format (ie if Date_Issued is a date column) or if it is a number column, then it will error.
The solution is to replace your dynamic SQL with a parameterized query eg:
String my_querry = "update crtPro set Name=#name, AR=#ar, Wereda=#Wereda, etc ...";
OleDbCommand cmd = new OleDbCommand(my_querry, conn);
cmd.Parameters.Clear();
cmd.Parameters.AddWithValue("#name", Name);
cmd.Parameters.AddWithValue("#myParam", Convert.ToDateTime(txtDate.Text.Trim()));
...
cmd.ExecuteNonQuery();
You can read about it further here
PS Make sure your parameters are in the same order as they are used in the SQL, because oledbcommand doesn't actually care what you call them. see here
How do you insert into a table in a .sdf database?
I've tried the following:
string connection = #"Data Source=|DataDirectory|\InvoiceDatabase.sdf";
SqlCeConnection cn = new SqlCeConnection(connection);
try
{
cn.Open();
}
catch (SqlCeException ex)
{
MessageBox.Show("Connection failed");
MessageBox.Show(ex.Message, Application.ProductName, MessageBoxButtons.OK, MessageBoxIcon.Error);
Application.ExitThread();
}
string clientName = txt_ClientName.Text;
string address = txt_ClientAddress.Text;
string postcode = txt_postcode.Text;
string telNo = txt_TelNo.Text;
string sqlquery = ("INSERT INTO Client (Name,Address,Postcode,Telephone_Number)Values(" + clientName + "','" + address + "','" + postcode + "','" + telNo + ")");
SqlCeCommand cmd = new SqlCeCommand(sqlquery, cn);
try {
int affectedRows = cmd.ExecuteNonQuery();
if (affectedRows > 0)
{
txt_ClientAddress.Text = "";
txt_ClientName.Text = "";
txt_postcode.Text = "";
txt_TelNo.Text = "";
MessageBox.Show("Client: " + clientName + " added to database. WOoo");
}
}
catch(Exception){
MessageBox.Show("Insert Failed.");
}
But it doesn't seem to matter what i do it just shows "Insert Failed".
Thanks in advance.
You forgot opening quotation mark on the first value.
Values(" + clientName + "','"
change to:
Values('" + clientName + "','"
But this is generally a bad way to build query. Use parametrized query instead.
See: http://msdn.microsoft.com/en-us/library/system.data.sqlserverce.sqlcecommand.parameters(v=vs.80).aspx
catch(Exception ex)
{
MessageBox.Show(ex);
}
Will give you more info on error.
It is the same old story. When you build a sql command concatenating string these kinds of errors abund. And the simple syntax problem is not the worst. The Sql Injection is the most dangerous one.
Please build your query in this way
string sqlquery = ("INSERT INTO Client (Name,Address,Postcode,Telephone_Number)" +
"Values(#client,#address, #postcode, #tel)";
SqlCeCommand cmd = new SqlCeCommand(sqlquery, cn);
cmd.Parameters.AddWithValue("#client", clientName);
cmd.Parameters.AddWithValue("#address", address);
cmd.Parameters.AddWithValue("#postcode", postcode);
cmd.Parameters.AddWithValue("#tel", telNo);
cmd.ExecuteNonQuery();
As others have already said your syntax error is caused by omitting the initial single quote. But you could have other errors. For example, what about a client called O'Hara?. Now you have a single quote inside the clientname and this wreak havoc your string concatenation.
Instead a parameter will be accurately parsed and every problematic character found will be treated appropriately (in this case doubling the single quote)
Your SQL statement is incorrect.
string sqlquery = ("INSERT INTO Client (Name,Address,Postcode,Telephone_Number)Values('" + clientName + "','" + address + "','" + postcode + "','" + telNo + "')");
Take this. You forgot the ' at the beginning and the end of the values
To insert data into Sql, data type should be considered. If you insert a string value (varchar) you have to surround it by single quotation, like '"+full_Name+"', but integer type doesn't need this. example
string myQuery = "INSERT INTO Persons (phone, fullname) VALUES ("+telNo+",'"+full_Name+"')";
where full name is string variable and phone number is only number.