System.Data.SqlClient.SqlException was unhandled by user code [closed] - c#

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SqlConnection conn = new SqlConnection(ConfigurationManager.ConnectionStrings["RegistrationConnectionString"].ConnectionString);
conn.Open();
string checkUser = " select count(*) form Userdata where Username='" + TextBoxUN.Text + "' ";
SqlCommand cmd = new SqlCommand(checkUser,conn);
if (temp==1)
{
Response.Write("User Already Exists");
}
conn.Close();
System.Data.SqlClient.SqlException was unhandled by user code
HResult=-2146232060 Message=Incorrect syntax near 'Userdata'
int temp= Convert.ToInt32(cmd.ExecuteScalar().ToString());

The error message says:
Incorrect syntax near 'Userdata'
That tells you that the SQL parser gave up at the word Userdata because the syntax no longer made sense, which usually means that the actual error is close before that word.
If you look at that part of your query:
select count(*) form Userdata
The word right before Userdata is form, but you should recognise that it's not the keyword from that you intended to write.
Side note (but an important one): The value that you concatentate into the query is not properly escaped, so the code is wide open to SQL injection attacks. You should use a parameter to put the value in the query:
string checkUser = "select count(*) from Userdata where Username = #Username";
SqlCommand cmd = new SqlCommand(checkUser,conn);
cmd.Parameters.AddWithValue("#Username", TextBoxUN.Text);

Related

Invalid column name 'e01' in SQL query [closed]

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Closed 7 years ago.
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i have database contain column name Code data type nvarchar(50) i connected to my database by c# and created a SQL command as
string code = "e01";
SqlCommand command = new SqlCommand("select * from inv where code = " + code + ";", conn);
SqlDataReader reader = command.ExecuteReader();
i found an error says
An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
Additional information: Invalid column name 'e01'.
and if i but number instead of e01 it work fine ..
your are missing quotes. Try this:
string code = "e01"
SqlCommand command = new SqlCommand("select * from inv where code = '" + code + "';", conn);
SqlDataReader reader = command.ExecuteReader();
Also, it's recomended use parameters instead concatenating values. This avoid sql injection attacks or sql errors if your code contains special characters, like quotes:
SqlCommand command = new SqlCommand("select * from inv where code = #pCode", conn);
command.Parameters.Add(new SqlParameter("#pCode", code));
SqlDataReader reader = command.ExecuteReader();
You forgot to put quotes around your column value, because e01 is a value and not a column it needs to be surrounded by single quotes.
SqlCommand command = new SqlCommand("select * from inv where code = '" + code + "';", conn);

c# to Access INSERT INTO query not working [closed]

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Closed 7 years ago.
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I am trying to enter the value of a textbox in c# into a field in a database that I have in access. For some reason I keep getting the error saying:
'An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll
Additional information: Syntax error in INSERT INTO statement.'
Can't quite see what is wrong, this is the first time I have attempted to do this in a project so I am not too experienced with it. This is my code:
OleDbConnection connection = new OleDbConnection(CONNECTION STRING GOES HERE);
connection.Open();
string playerName = textBox[i].Text;
string query = "INSERT INTO (TotalPlayerName)(Player Name) VALUES(" + playerName + ")";
OleDbCommand command = new OleDbCommand(query, connection);
command.ExecuteNonQuery();
if it helps then the database is called 'Database' the table is called 'TotalPlayerName' and the field is called 'Player Name'
The correct code to do your task is
string cmdText = "INSERT INTO TotalPlayerName ([Player Name]) VALUES(?)";
using(OleDbConnection connection = new OleDbConnection(...))
using(OleDbCommand command = new OleDbCommand(cmdText, connection))
{
connection.Open();
command.Parameters.Add("#p1", OleDbType.VarWChar).Value = textBox[i].Text;
int result = command.ExecuteNonQuery();
if(result > 0)
MessageBox.Show("Record Inserted");
else
MessageBox.Show("Failure to insert");
}
This approach fixes three problems:
The connection and the command object should be disposed at the end
(see using statement)
Every value that you need to pass to the query should be passed as
parameter
If a field name (or table name) has embedded spaces you should enclose
it between square brackets
(The messages below the ExecuteNonQuery are there only as an example to check the return value of ExecuteNonQuery)
Remember also that if your table has more than this field and some of the other fields don't accept null values you should provide some value also for them.
For example
string cmdText = #"INSERT INTO TotalPlayerName ([Player Name], FieldB)
VALUES(?, ?)";
command.Parameters.Add("#p1", OleDbType.VarWChar).Value = textBox[i].Text;
command.Parameters.Add("#p2", OleDbType.VarWChar).Value = "ValueForFieldB";
Just remember to strictly follow the order of the ? when you add your parameter values

Incorrect syntax near 's' [closed]

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Closed 8 years ago.
Edit the question to include desired behavior, a specific problem or error, and the shortest code necessary to reproduce the problem. This will help others answer the question.
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I get an error on sc.ExecuteNonQuery();.. Error: Incorrect syntax near 's'
Code:
con = new SqlConnection("Data Source=DELL-PC;Initial Catalog=sashi;Integrated Security=True");
con.Open();
SqlCommand sc = new SqlCommand("INSERT INTO Login VALUES('" + textBoxUID.Text + "','" + textBoxPWD.Text + "','" + comboBoxQUN.Text + "','" + textBoxANS.Text + "' ) ", con);
sc.ExecuteNonQuery();
MessageBox.Show("Record has been inserted");
con.Close();
What I forgot or where is the error?
Please Use Parameters like this:
using (var con = new SqlConnection("Data Source=DELL-PC;Initial Catalog=sashi;Integrated Security=True"))
{
con.Open();
using(var sc = connection.CreateCommand())
{
sc.CommandText = "INSERT INTO Login VALUES(#uid,#pass,#qun,#ans)";
sc.Parameters.Add(new SqlParameter("#uid", textBoxUID.Text));
sc.Parameters.Add(new SqlParameter("#pass", textBoxPWD.Text));
sc.Parameters.Add(new SqlParameter("#qun", comboBoxQUN.Text));
sc.Parameters.Add(new SqlParameter("#ans", textBoxANS.Text));;
sc.ExecuteNonQuery();
}
}
Sql parameters helps prevent SQL Injection attacks.. and ist easier to read..
Does your login table have only four columns? otherwise you must also specify this in your insert-statement: INSERT INTO (col1, col2 ....

how to assign select result to variable c# [closed]

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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 making GUI for a database (school project) and I have following problem - when i try to assign resul from select statement to variable i have strange error:
An unhandled exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll
Additional information: Incorrect syntax near ')'.
this is my code:
string sql2 = "SELECT * FROM Car WHERE Make = '#CarID' AND Model = '#CarID2');";
SqlCommand cmd3 = new SqlCommand(sql2, sqlconn);
cmd3.Parameters.AddWithValue("#CarID", model_cbo);
cmd3.Parameters.AddWithValue("#CarID2", make_cbo);
string CarID = cmd3.ExecuteScalar().ToString();
I've looking for the solution for a long time, but haven't found anything, so please help
This is my code for connection with DB:
public CarSpec()
{
InitializeComponent();
connectDB();
this.conn = new OleDbConnection("PROVIDER=SQLOLEDB;Data Source=HENIU;Initial Catalog=ServiceStation; Integrated Security=SSPI;");
conn.Open();
}
public void connectDB()
{
sqlconn = new SqlConnection(#"Data Source=HENIU; Initial Catalog=ServiceStation; Integrated Security=TRUE;");
sqlconn.Open();
da = new SqlDataAdapter();
}
There are three problems in your code:
There is a parenthesys not needed at the end of the WHERE clause
The parameters should be free from the single quotes. (Otherwise the will be treated as string literals)
The ExecuteScalar returns just a the first column of the first row.
You cannot be certain that this will be the carID.
Use instead
string sql2 = "SELECT * FROM Car WHERE Make = #CarID AND Model = #CarID2";
SqlCommand cmd3 = new SqlCommand(sql2, sqlconn);
cmd3.Parameters.AddWithValue("#CarID", model_cbo);
cmd3.Parameters.AddWithValue("#CarID2", make_cbo);
SqlDataReader reader = cmd3.ExecuteReader()
if(reader.Read())
{
int carID = Convert.ToInt32(reader["CarID"]);
}
Here I am assuming that a carID is a number and not a string (as it should be). However, if it is a string then you could change the line to
string carID = reader["CarID"].ToString();

An expression of non-boolean type specified in a context where a condition is expected, near 'Name' [closed]

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The line that beings int temp = Convert... is giving the error:
An expression of non-boolean type specified in a context where a condition is expected, near 'Name'
The surrounding code is:
String checkuser = "select count(*) from [UserRecord] where User Name= " +TextBoxUsername.Text + "";
SqlCommand com = new SqlCommand(checkuser, conn);
int temp = Convert.ToInt32(com.ExecuteScalar().ToString()); //error on this line
if (temp == 1)
Can someone explain what is causing the error?
You need to surround the username with single quotes.
String checkuser = "select count(*) from [UserRecord] where User Name= '" +TextBoxUsername.Text + "'";
Also, User Name shouldn't have a space in it, or needs [] around it.
Or better yet, use a parameterized query.
Please check your query.there is a space between User and Name for username.
"select count(*) from [UserRecord] where User Name= "
You forget '
String checkuser = "select count(*) from [UserRecord] where User Name= '" +TextBoxUsername.Text + "'";

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