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I'm developing a c# windows form application program that saves the info about the student like name course year and etc. My code in saving to sql database works but when it comes to retreiving the info i get these error incorrect syntax near '='. i think the error is in the retreive code.please help :)
Here is the retrieve code:
try
{
string sql = "SELECT studnum,course,f_name,l_name,color_image FROM table3 WHERE f_name=" + textBoxfname.Text + "";
if (conn.State != ConnectionState.Open)
conn.Open();
command = new SqlCommand(sql, conn);
SqlDataReader reader = command.ExecuteReader();
reader.Read();
if (reader.HasRows)
{
labeloutputstudnum.Text = reader[0].ToString();
labeloutputcourse.Text = reader[1].ToString();
labeloutputfname.Text = reader[2].ToString();
labeloutputlname.Text = reader[3].ToString();
byte[] img = (byte[])(reader[4]);
if (img == null)
pictureBox3.Image = null;
else
{
MemoryStream ms = new MemoryStream(img);
pictureBox3.Image = Image.FromStream(ms);
}
}
else
{
textBoxstudno.Text = "";
textBoxcourse.Text = "";
textBoxfname.Text = "";
textBoxlname.Text = "";
pictureBox3.Image = null;
MessageBox.Show("does not exist");
}
conn.Close();
}
catch (Exception ex)
{
conn.Close();
MessageBox.Show(ex.Message);
}
string sql = "SELECT studnum,course,f_name,l_name,color_image FROM table3 WHERE f_name=#Name";
command = new SqlCommand(sql, conn);
command.Parameters.Add(new SqlParameter("#Name", textBoxfname.Text));
I see multiple errors:
The most obvious, always use parameters in your sql statements.
Always use using blocks to clean up connections.
Do not reuse connections, this is bad practice as sql server will automatically (by default unless you turn it off exclititly) use connection pooling.
// DO NOT reuse connections, create a new one when needed!
using(var conn = new SqlConnection(/use a connection from the web/app .config/))
{
const string sql = "SELECT studnum,course,f_name,l_name,color_image FROM table3 WHERE f_name = #name";
command = new SqlCommand(sql, conn);
command.Parameters.Add(new SqlParameter("#name", SqlDbType.VarChar) { Value = textBoxfname.Text});
conn.Open();
/* rest of code unchanged but do not call conn.Close(), the using block will do this for you
}
So to answer your question, your sql query has incorrect syntax. I would break point on the sql string to see exactly what's wrong. It should be obvious when you do that.
The REAL problem though is that you're exposing your application to SQL injection. Let's look at a basic example of what you have.
"SELECT * FROM table WHERE id ='" + userinput.Text + "'";
So the user inputs some value and it gets dumped in there for the query. Simple right?
What happens if the user inputs this
' OR 1=1; --
Well let's see what your sql string turns into when that's added
SELECT * FROM table WHERE id = '' OR 1=1; -- '
So now, your query string says select the id OR where 1=1 which means where true, which means everything.
SQL injection is a real threat and the only way to stop it is to implement counter measures right from the start.
Please look into parameterization. It's very easy in C#.
MSDN Article on C# Parameterization
You have to use single quotes for string parameters/fields in SQL:
string sql = "SELECT studnum,course,f_name,l_name,color_image FROM table3 WHERE f_name='" + textBoxfname.Text + "'";
But it is better (more secure) to use parameters:
string sql = "SELECT studnum,course,f_name,l_name,color_image FROM table3 WHERE f_name=#name";
if (conn.State != ConnectionState.Open)
conn.Open();
var command = new SqlCommand(sql, conn);
command.Parameters.Add("#name", SqlDbType.NVarChar).Value = textBoxfname.Text;
Related
Is there anything wrong with my codes? Because, I'm about to create a login form and it doesn't.
OleDbConnection conDataBase = new OleDbConnection(#"Provider=Microsoft.ACE.OLEDB.12.0; Data Source = C:\Users\tess\Documents\iknow.accdb;" + "Persist Security Info = True");
OleDbCommand cmdDataBase = new OleDbCommand(" select * from iknow where Username = '"+user_NameTextBox.Text+"'");
cmdDataBase.Connection = conDataBase;
OleDbDataReader myReader;
conDataBase.Open();
myReader = cmdDataBase.ExecuteReader();
int count = 0;
while (myReader.Read())
{
count = count + 1;
}
if (count == 1)
{
MessageBox.Show("Login Successful");
}
else
{
MessageBox.Show("Invalid Username");
}
You have a couple issues, as Jon Skeet pointed out you've introduced a SQL injection vulnerability, aren't implementing the using syntax to dispose of resources correctly, and have a parameter but aren't actually implementing (this is hard to identify, without more code or what flagged this error).
var query = "SELECT TOP 1 [Id] FROM User WHERE Username = #Username";
using(var connection = new OleDbConnection(path))
using(var command = new OleDbCommand(query, connection))
{
connection.Open();
command.Parameters("Username", txtUsername.Text());
using(var reader = command.ExecuteReader())
while(reader.Read())
{
// Do something.
}
}
So the above code would address the following:
Injection point
Disposing resources
Correctly associating command to connection
No reason to * for everything, if you only want to see if it exists.
You should really only have a single username, so TOP 1 could refine.
You also could use ExecuteScalar instead of reader, that way you can simply validate the record was returned. This would alleviate the need to iterate through the returned record set. If you TOP 1 and ensure only one username exists, won't matter but it is an option.
As for your parameter, we would need more information. The debugger should tell you which line is throwing the exception. Those details could help resolve the issue.
C#, Razor
my code is:
#using (SqlConnection Praktikum2 = new SqlConnection("Data Source=Mark\\SQLEXPRESS;Initial Catalog=Connection;Integrated Security=True"))
{
using(connection)
{
SqlCommand command = new SqlCommand("SELECT KategoryID FROM Kategory WHERE Name = " + Request.Params["kategory"]);
connection.Open();
SqlDataReader reader = command.ExecuteReader(); //ERROR!!!
while (reader.Read())
{
string ID = reader["KategorieID"].ToString() ;
Console.WriteLine("ID = {0}", ID);
}
reader.Close();
};
}
i get an error that there's a wrong syntax near "=".
how can i solve this?
The problem is caused by the missing quotes around the value passed for your search. You could add a set of single quote before and after the value obtained by the Request but that would be a bigger error and the source of a problem called Sql Injection.
The only way to handle this is to use a parameter query
SqlCommand command = new SqlCommand(#"SELECT KategoryID FROM Kategory
WHERE Name = #name", connection);
command.Parameters.Add("#name", SqlDbType.NVarChar).Value = Request.Params["kategory"];
Also, as noted in another answer, your code seems to not have associated the connection to the command, I think that it is just a typo here because the error message in that case would be 'need an open connection'
You forgot to assign the connection to the command. So when you call ExecuteReader(), it does not know on which connection it should be executed.
You can assign the connection like this:
SqlCommand command = new SqlCommand(
"SELECT KategoryID FROM Kategory WHERE Name = " + Request.Params["kategory"],
connection); // provide connection as second parameter!
or use connection.CreateCommand() to create your command.
Second, you forgot the quotation marks around your string:
"SELECT KategoryID FROM Kategory WHERE Name = '" + Request.Params["kategory"] + "'"
but inserting user data directly into your query opens your code to SQL Injection. Please use parameterized queries instead.
If your kategory column is not of integer data type then you need to surround your value with (') i.e single quote characters
Then your query will be like
SqlCommand command = new SqlCommand("SELECT KategoryID FROM Kategory WHERE Name ='" + Request.Params["kategory"] + "'");
The exception is caused by how you are creating your sql statement. The fix should not be correcting the syntax but using parameters instead. This will prevent sql injection attacks.
Also
You really should not be writting sql in your views, do it in your controller method instead and return the result in the Model to be used in your view. Better yet, abstract it to a different layer and call that layer from your controller. This has to do with SoS (Separation of Concerns), your code will very difficult to maintain if you just write everything into your views.
Wrap your connections, commands, and readers in using blocks.
Modified Code
#{
using(SqlConnection Praktikum2 = new SqlConnection("Data Source=Mark\\SQLEXPRESS;Initial Catalog=Connection;Integrated Security=True"))
using(SqlCommand command = new SqlCommand("SELECT KategoryID FROM Kategory WHERE Name = #name", Praktikum2))
{
command.Parameters.Add(new SqlParameter("#name", SqlDbType.VarChar){ Value = Request.Params["kategory"]});
connection.Open();
using(SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
string ID = reader["KategorieID"].ToString() ;
Console.WriteLine("ID = {0}", ID);
}
}
}
}
Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 6 years ago.
Improve this question
I'm getting a weird syntax error when trying to view an image from the database. It is statement an incorrect syntax error near an operator. I have no idea what is happening as im pretty sure this is all fine until it runs.
"incorrect syntax near '= "
View image code
using (SqlConnection con = new SqlConnection(#"Data Source=(LocalDB)\v11.0; AttachDbFilename=C:\Users\Donald\Documents\Visual Studio 2013\Projects\DesktopApplication\DesktopApplication\Student_CB.mdf ;Integrated Security=True"))
{
con.Open();
try
{
string sql = "Select Image, Image_Name FROM Recipe_Image Where Image_ID =" + imageidTxt.Text + "";
if (con.State != ConnectionState.Open)
con.Open();
command = new SqlCommand(sql, con);
SqlDataReader reader = command.ExecuteReader();
reader.Read();
if(reader.HasRows)
{
nameTxt.Text = reader[0].ToString();
byte[] img = (byte[])(reader[1]);
if (img == null)
picImg.Image = null;
else
{
MemoryStream ms = new MemoryStream(img);
picImg.Image = Image.FromStream(ms);
}
}
con.Close();
}
catch (Exception e)
{
MessageBox.Show(e.Message);
}
con.Close();
}
Your SQL syntax is invalid, mostly because you're not actually in control of it. (You have what's called a SQL Injection Vulnerability.) Instead of executing user-input values as code, treat them as values. First, define a static query with a parameter placeholder:
string sql = "Select Image, Image_Name FROM Recipe_Image Where Image_ID = #Image_ID";
Then when you build your SqlCommand object, add a parameter for that placeholder:
// the query implies that the ID is a number, so make it a number...
int imageId = 0;
if (!int.TryParse(imageidTxt.Text, out imageId)
{
// entered text wasn't a number, return an error?
}
// then add that number as a parameter
command.Parameters.Add("#Image_ID", SqlDbType.Int).Value = imageId;
This way you've defined a static query at design-time, rather than building a dynamic (and currently unknown) one at runtime. So the syntax of the SQL query is known and can be validated as part of the design.
Note: This answer has been changed pretty heavily to correct some misinformation.
Previously, this answer suggested using Convert.ToInt32(x). This will not directly pass an integer to the database; however, it will happily yell at you (throw an exception) if the value passed in is not an integer.
What does happen is that the query string is passed down to sql (as a string) and the sql parser interprets the value as an int based on (little sql goblins).
Instead, you should probably be doing something more like this:
public void ReadFromDatabase()
{
int idToFind;
//check that imageidTxt.Text is an integer
if (Int32.TryParse(imageidTxt.Text, out idToFind))
{
//we have an integer, so look at the database
string sql = "SELECT * FROM Table WHERE ID=" + idToFind;
//connect to/read from DB
}
else
{
//fail spectacularly
}
}
This will add (trivial) error checking before you hit the database, and pass in the query as valid syntax.
Note that this answer does not address issues like SQL Injection that have been brought up in comments/answers, and even if it doesn't make much sense to you at the moment, it's very much worth learning about.
I have an ASP webpage that gets a string from the user. These strings are usually complex SQL queries or code snippets, so I need to insert them into database with the characters like \n, \r. And then read it in the same format so all another user has to do is copying the code and running it.
Problem is, when inserting to database, they are cut. I am using SQL Server, here is my code for inserting to database:
OdbcConnection conn = new OdbcConnection();
StringBuilder query = new StringBuilder();
OdbcCommand command = new OdbcCommand();
string db= null;
db = connectionstr;
conn.ConnectionString = veritabani;
conn.Open();
db = null;
string detail = this.txtdetail.Text;
command = conn.CreateCommand();
if (string.IsNullOrEmpty(hdnFilename.Value))
{
query.Append(" INSERT INTO SUPPORT (title, detail, date) VALUES (?,?,?) ");
command.CommandText = query.ToString();
command.Parameters.Add("#title", OdbcType.VarChar).Value = this.txtbaslik.Text;
command.Parameters.Add("#detail", OdbcType.NVarChar).Value = detail;
command.Parameters.Add("#date", OdbcType.DateTime).Value = DateTime.Now.ToString();
}
else
{
query.Append(" INSERT INTO SUPPORT (baslik, detail, date, file) VALUES (?,?,?,?) ");
command.CommandText = query.ToString();
command.Parameters.Add("#title", OdbcType.VarChar).Value = this.txtbaslik.Text;
command.Parameters.Add("#detail", OdbcType.NVarChar).Value = detail;
command.Parameters.Add("#date", OdbcType.DateTime).Value = DateTime.Now.ToString();
command.Parameters.Add("#file", OdbcType.VarChar).Value = hdnFilename.Value;
}
command.ExecuteNonQuery();
command = null;
conn.Close();
conn = null;
Code works fine and inserts into the database, had to translate a few variables to give you guys a better idea, original has no syntax errors.
The thing is, sql statements had comment lines in them, so if I were to copy paste the query, It would not work. Removing them helped, I will leave the question here for future generations. Thank you for the answers.
Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 8 years ago.
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I'm getting a run time error in my program when connecting to a SQL Server CE database.
Can anyone help me, and please don't write the whole code just a line of what needs to be changed to.
Here is my code:
string conString = Properties.Settings.Default.POSdatabaseConnectionString;
using (SqlCeConnection con = new SqlCeConnection(conString))
{
con.Open();
using (SqlCeCommand com = new SqlCeCommand("SELECT * FROM Customer where Customer ID ='" + this.useridtexbox.Text + "' and Name='" + this.nametexbox.Text + "'", con))
{
SqlCeDataReader reader = com.ExecuteReader();
int count = 0;
while (reader.Read())
{
count = count + 1;
}
if (count == 1)
{
MessageBox.Show("You have logged in succesfully");
Homepage homepage = new Homepage();
homepage.Show();
homepage.LabelText = ("Welcome " + reader["name"].ToString());
}
else
{
MessageBox.Show("Username and password is Not correct ...Please try again");
con.Close();
}
Error:
There was an error parsing the query. [ Token line number = 1,Token line offset = 39,Token in error = ID ]
I think the problem with the space in Customer ID,Try this
SqlCeCommand com = new SqlCeCommand("SELECT * FROM Customer where CustomerID ='" + this.useridtexbox.Text + "' and Name='" + this.nametexbox.Text + "'", con))
In your command, do not use string concatenation. That will fail badly and leave you open to SQL injection attacks.
Image what happens if I enter the following text into this.nametexbox.Text:
Joe'; DROP DATABASE; --
You don't want have someone like little Bobby Tables as user.
Use sql parameters.
If you have tables or fields with spaces, you to have a word with your DBA. If you cannot change it, make sure you use the correct syntax:
WHERE [Customer ID] = '12345'
Make sure you CustomerID column have space
Always use parameterized query to avoid SQL Injection
How does SQLParameter prevent SQL Injection
SqlCeCommand com = new SqlCeCommand = "SELECT * FROM Customer where CustomerID=#CustomerID and
name=#name";
con.Parameters.AddWithValue("#CustomerID", valuesTextBox.Text);
con.Parameters.AddWithValue("#name", namwTextBox.Text);