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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.
Related
This question already has answers here:
What are good ways to prevent SQL injection? [duplicate]
(4 answers)
Closed 1 year ago.
I've been stuck on this issue for a few hours and I can't seem to get over what is causing this issue to populate. When running my application in debug mode, it will run the foreach two times successfully returning "Query Executed!".
However, when it goes for the third time, I get this error:
Incorrect syntax near ']'.Unclosed quotation mark after the character string '')'.
My method that will perform the insert to the SQL Server table Logs:
static String connectionString = "Data Source=.\\SQLExpress;Database=ElasticSearchService;Trusted_Connection=True;";
public static async Task<int> InsertLogData()
{
SqlConnection connection = null;
SqlCommand command = null;
int numrows = 0;
try
{
var response = await _elasticClient.SearchAsync<EsSource>(s => s
.Size(3000)
.Source(src => src.Includes(i => i
.Fields(f => f.timestamp,
fields => fields.messageTemplate,
fields => fields.message)))
.Index("customer-simulation-es-app-logs*")
.Query(q => +q
.DateRange(dr => dr
.Field("#timestamp")
.GreaterThanOrEquals("2021-06-07T17:13:54.414-05:00")
.LessThanOrEquals(DateTime.Now))));
// var json = _elasticClient.RequestResponseSerializer.SerializeToString(response);
connection = new SqlConnection(connectionString);
Console.WriteLine("\nOpening connection...");
connection.Open();
Console.WriteLine("\nConnection successful!");
foreach (var item in response.Hits)
{
var dateCreated = item.Source.timestamp;
var messageTemplate = item.Source.messageTemplate;
var message = item.Source.message;
command = new SqlCommand("insert into Logs (DateCreated, MessageTemplate, Message) values ('" + dateCreated + "', '" + messageTemplate + "', '" + message + "')", connection);
numrows = command.ExecuteNonQuery();
Console.WriteLine("\nQuery Executed!");
}
connection.Close();
Console.WriteLine("\nConnection Closed....");
}
catch (Exception ex)
{
Debug.WriteLine(ex.Message);
}
finally
{
command.Dispose();
connection.Dispose();
}
return numrows;
}
Is there something that is causing this that I am not seeing? Is my command = new SqlCommand() incorrect that is causing it to come with that error of:
Incorrect syntax near ']'.Unclosed quotation mark after the character string '')'.
For starters:
command = new SqlCommand("insert into Logs (DateCreated, MessageTemplate, Message) values (#dt, #mt, #m)";
command.Parameters.AddWithValue("#dt", dateCreated);
command.Parameters.AddWithValue("#mt", messageTemplate);
command.Parameters.AddWithValue("#m", message);
Then execute it
After you get comfortable with that, take a read of this blog - AddWithValue is convenient but it can cause performance issues in some contexts. I don't care about it so much for something like an insert statement but I'd recommend you read the blog to see why you should move away from making a habit of it in SQL Server, once you're down with how parameterizing works. Also worth noting that not every database has issues with AWV, and to some great extent it is preferable to use it and suffer occasional performance issues than not use parameterizing at all and get hacked
SQL in the way you've got it (and the way I've got it) adding parameters etc is actually fairly tedious. Take a look at dapper, a library that makes it a lot easier to do this sort of stuff and more, such as running a sql query and turning the result setinto a list of c# objects, a bit like parsing Json
Other things to consider:
use of ExecuteNonQueryAsync
create your command outside of the foreach loop and add dummy parameters of the right types using AddWithValue (or take the fine opportunity to branch out into adding carefully constructed parameters of the right sql db type), then open the connection and run the loop, changing the parameter values on every pass of the loop. In summary: setup once, change the values and execute 1000 times, rather than setting up 1000 times
use using to declare your command, that way it gets disposed later
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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;
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Thanks to Nate M. I've got this running, using the second part of code, and some schooling in SQL Server (it's my first day)
So it's solved. Thank you everyone for the help.
I can't figure this out. I'm using Visual Studio 2015, SQL Server 2014, that works, but I can't figure out how to insert data on the click of a button. I've tried stuff on MSDN, nothing works, they have about 100 different ways. I'm confused. Here's what I've got.
private void btnTheWorst_Click(object sender, EventArgs e)
{
lblMood.Text = "The Worst :(";
lblMood.ForeColor = System.Drawing.Color.Navy;
SqlConnection cmood = new SqlConnection("my connection string"); {
cmood.Rows.Add(new Object[] { 1, "Smith" });
}
This is where I get the error.
SqlConnection does not contain a definition for 'Rows' and no extension method 'Rows' accepting a first argument of type 'SqlConnection' could be found.
The comments are completely correct. There is a particular sequence of events you need to do to interact with a database. I keep a piece of code on a scratch pad because I use it so much which outlines the basic structure of what you need to be doing.
using(var conn = new SqlConnection(<connection string here>))
{
try
{
conn.Open();
string sql = "<sql query here>";
using(var cmd = new SqlCommand(sql,conn))
{
using(var reader = cmd.ExecuteReader())
{
if(reader.HasRows)
{
while(reader.Read())
{
//Here is where you get your data..
int imReadingAnInt = (int)reader["myIntColumnHeader"];
string imReadingAString = reader["myStringColumnHeader"].ToString();
}
}
}
}
}
catch (Exception ex)
{
string err = ex.Message;
}
}
On inserts:
You can draft a sql insert using the above method, and use cmd.ExecuteNonQuery() to perform the insert. An Example..
using(var conn = new SqlConnection(<connection string here>))
{
try
{
conn.Open();
string sql = "insert into [table_name] values (#column1Value,#column2Value,...);";
using(var cmd = new SqlCommand(sql,conn))
{
cmd.Parameters.AddWithValue("#column1Value",1);//Presuming column 1 is an int
cmd.Parameters.AddWithValue("#column2Value","Smith"); //Presuming column 2 is a varchar (string)
cmd.ExecuteNonQuery();
}
}
catch (Exception ex)
{
string err = ex.Message;
}
}
Note the above code uses paramaterization (sp) to prevent SQL injection. You could hard code the values into the SQL Query string, but it is not considered best practices from a security standpoint.
W3 Schools SQL Insert
My brain keeps churning on this.. Just a note on the fundamental concepts here. With the Objects SqlConnection, SqlCommand etc, you are not actually establishing direct access to the database (ie you can't just go grab a row and manually edit it). Instead, you are setting up a connection through which you can perform SQL queries which are a well structured method of reading and editing the database. There is of course tons of information out there on how to construct said queries, so once you understand the purpose of the C# objects in question, accessing and changing a database will make a lot more sense.
Check this out, which gives fair knowledge on how to insert data to database.
You can check Insert New Records Using Command Objects section
https://msdn.microsoft.com/en-us/library/ms233812.aspx
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Hi i have problem with execute Query with Parameter in access database:
OleDbConnection cnn;
OleDbCommand cmdselect2;
string sqlselect2 = null;
string baza = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + #"L:\Windykacja\Sdro\Projekt\projekt.accdb";
connetionString = baza;
sqlselect2 = "SELECT count(POS_Pesel_regon) as Suma FROM POS WHERE POS_Pesel_regon = #PR";
cnn = new OleDbConnection(connetionString);
cnn.Open();
cmdselect2 = new OleDbCommand(sqlselect2, cnn);
Int32 PR1 = Convert.ToInt32(cmdselect2.ExecuteScalar());
cmdselect2.Parameters.AddWithValue("#PR", textBox6.Text);
cmdselect2.Dispose();
cnn.Close();
It's say that my paramter is missing
In insert it works perfectly :)
will be thankfull for any sugestions.
cheers
Because you try to execute your command before you add your parameter. Change those lines
Int32 PR1 = Convert.ToInt32(cmdselect2.ExecuteScalar());
cmdselect2.Parameters.AddWithValue("#PR", textBox6.Text);
to
cmdselect2.Parameters.AddWithValue("#PR", textBox6.Text);
Int32 PR1 = Convert.ToInt32(cmdselect2.ExecuteScalar());
A few things more;
Use using statement to dispose your connection and command automatically instead of calling Close or Dispose methods manually.
Don't use AddWithValue as much as you can. It may generate unexpected and surprising results sometimes. Use Add method overload to specify your parameter type and it's size.
using(var cnn = new OleDbConnection(connetionString))
using(var cmdselect2 = cnn.CreateCommand())
{
cmdselect2.CommandText = #"SELECT count(POS_Pesel_regon) as Suma FROM POS
WHERE POS_Pesel_regon = #PR";
cmdselect2.Parameters.Add("#PR", OleDbType.VarChar).Value = textBox6.Text;
// I assumed your column type as VarChar
cnn.Open();
int PR1 = (int)cmdselect2.ExecuteScalar();
}
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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);