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 4 years ago.
Improve this question
Im trying to retrieve no of rows from sql based user input & display in gridview
Please help!
Int32 text = Convert.ToInt32(this.Txtusers.Text);
con.Open();
cmd = new SqlCommand("select TOP '" + text + "' * from Avaya_Id where LOB = '" + DDLOB.SelectedItem.Value + "' and Status = 'Unassigned'", con);
SqlDataReader rdr = cmd.ExecuteReader();
GridView1.DataSource = rdr;
GridView1.DataBind();
con.Close();
Here is how it should be written.
int text;
if(int.TryParse(this.Txtusers.Text, out text)
{
using(var con = new SqlConnection(connectionString)
{
using(var cmd = new SqlCommand("select TOP (#top) * from Avaya_Id where LOB = #LOB and Status = 'Unassigned'", con))
{
cmd.Parameters.Add("#top", SqlDbType.Int).Value = text;
cmd.Parameters.Add("#LOB", SqlDbType.Int).Value = DDLOB.SelectedItem.Value;
con.Open();
using(var rdr = cmd.ExecuteReader())
{
GridView1.DataSource = rdr;
GridView1.DataBind();
}
}
}
}
Points of interest:
Using parameters to avoid the risk of Sql Injection.
Changed Convert.ToInt32 to int.TryParse. Never trust user input.
Use the using statement for every instance that implements the IDisposable interface.
Please note that using top x without an order by clause means you get x arbitrary records from the database - since database tables are unordered by nature and the only way to ensure the order of the rows returned from a select statement is to use the order by clause.
Please note I've guessed that the second parameter is an int, if it's not, change the data type.
Related
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 1 year ago.
Improve this question
This is my code:
private void button1_Click(object sender, EventArgs e)
{
SqlConnection con = new SqlConnection();
con.ConnectionString = "data source = LAPTOP-ULT25NKH; database = college;integrated security = True";
SqlCommand cmd = new SqlCommand();
cmd.Connection = con;
cmd.CommandText = "select * from teacher where tID = " + textBox1.Text + "";
DataSet DS = new DataSet();
SqlDataAdapter DA = new SqlDataAdapter(cmd);
DA.Fill(DS);
dataGridView1.DataSource = DS.Tables[0];
}
but I get this exception:
An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll but was not handled in user code
Additional information: Incorrect syntax near '='."
Ensure you are properly santizing inputs and using prepared statements; to start down the line for you, try:
cmd.CommandText = "SELECT * FROM teacher WHERE tID = #tID;"
SqlParameter idParam = new SqlParameter("#tID", SqlDbType.NVarChar , 0);
idParam.Value = textBox1.Text;
cmd.Parameters.Add(idParam);
cmd.Prepare();
There are lot of issues in your existing code, I’m mentioning few points brlow.
Please move the connection string to some config file, it’s easy to maintain there.
When you have DataAdapter you don’t need to explicitly open the connection, it does that for you internally.
Please avoid * in select query, mention the columns with alias and use parameterized query to pass the parameters. Or your can write stored procedure and call it. So that I if I’m future you need to modify query, there will be no code change.
If you need to open the connection, please close it or your can use using.
You can add breakpoint and see the value of your query and if you copy this query value and run in sql server directly . This is one way to find the error in the query.
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 5 years ago.
Improve this question
I've got a database that has two columns both are of type int.
One column is called "id" and the other "counter".
Im using an SQLDataReader to read from the database
int id = (int)reader3["id"];
int counter = (int)reader3["counter"];
The first variable "id" returns the id value of the column fine. But the second variable stops the execution with a System.IndexOutOfRangeException: 'counter' error.
I cant really debug this error as counter does not exist in the current context.
con.Open();
SqlCommand cmd2 = new SqlCommand("SELECT id FROM categoryData WHERE CONVERT(DATE,Date) = CONVERT(DATE,GETDATE(),103) AND category = '" +
categoryList[i] + "'", con);
cmd2.ExecuteNonQuery();
SqlDataReader reader3 = cmd2.ExecuteReader();
while (reader3.Read())
{
int id = (int)reader3["id"];
int counter = (int)reader3["counter"];
cmd2.Parameters.Clear();
con.Open();
cmd2 = new SqlCommand("UPDATE categoryData SET counter = counter+1 WHERE
id = " + id + "", con);
cmd2.ExecuteNonQuery();
dateLabel.Text = categoryBox.SelectedItem.ToString();
recordedLabel.Text = "Count is: " + counter;
break;
}
The error actually means the your select statement does not contain a column named counter in it from whatever table you are selecting the data.
So what you need to do is carefully check your query that it is returning a column named counter of type int.
The query associated with reader3 should be something like:
select id, counter from categoryData
where .......
UPDATE:
So from your updated questions it is quite clear now that you are not selecting counter column in your query which probably you missed when adding query, so it should be :
SqlCommand cmd2 = new SqlCommand("SELECT id,counter FROM categoryData WHERE
CONVERT(DATE,Date) = CONVERT(DATE,GETDATE(),103) AND category = '" +
categoryList[i] + "'", con);
Important Caution!
and one more thing that is important here is that do not do string concatenation in your queries, instead use Parameterized queries to be safe from SQL Injection.
Following would be the code to with Parameterized query :
SqlCommand cmd2 = new SqlCommand("SELECT id,couter FROM categoryData WHERE CONVERT(DATE,Date) = CONVERT(DATE,GETDATE(),103) AND category = #category",con);
cmd2.Parameters.AddWithValue("#category", categoryList[i]);
cmd2.ExecuteNonQuery();
Hope it helps!
Your problem is your query.
"SELECT id FROM categoryData ..." "counter" isn't one of your fields you're retrieving. It needs to say:
"SELECT id, counter FROM categoryData ..."
SELECT id, counter FROM categoryData WHERE...
EDIT: string concatenation in SqlQuery is not the best idea, this can be use to SqlInjection...
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 have set up a mySql database on a server, and now i want to reach it in order for me to make a webservice. Firstly i just want to test if i can grab an entity from my query in my method (OneEntity), and put it into my list.
public IEnumerable<Person> Get()
{
return new List<Person> {
new Person{ ID = 0, First = OneEntity(), Last ="Example"}
};
}
public string OneEntity()
{
MySql.Data.MySqlClient.MySqlConnection mySqlConnection;
MySql.Data.MySqlClient.MySqlCommand cmd;
String connString = System.Configuration.ConfigurationManager.ConnectionStrings["MySql"].ToString();
mySqlConnection = new MySql.Data.MySqlClient.MySqlConnection(connString);
cmd = new MySql.Data.MySqlClient.MySqlCommand();
cmd.CommandText = "SELECT 'name' FROM 'CustomerDb' WHERE 'id' = 0";
cmd.CommandType = CommandType.Text;
cmd.Connection = mySqlConnection;
mySqlConnection.Open();
SqlDataReader reader = cmd.ExecuteReader();
mySqlConnection.Close();
return reader;
}
I am not very experienced in c# and are therefore not sure if im doing it correct. However in my cmd.ExecuteReader() (Object i guess it is?!??!) i get that it
cannot implicitly convert type 'MySql.Data.MySqlDataReader' to
'System.Data.SqlClient.SqlDataReader'
What am i doing wrong here?? obviously my return is not correct either, as i specified my method to be 'string'.. but even though i type in a string, the error doesn't dissapear?
you shoud use MySqlDataReader not SqlDataReader
MySqlDataReader Reader = cmd.ExecuteReader();
code should return string not the reader in your case.
To return the first item use this return reader.GetString(0);
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 7 years ago.
Improve this question
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);
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.
Improve this question
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();