I am doing a project with C# and I have this error:
MySql.Data.MySqlClient.MySqlException (0x80004005): You have an error
in your SQL syntax; check the manual that corresponds to your MariaDB
server version for the right syntax to use near ' last_name= , email=
, phone= , address= WHERE id= 6' at line 1
I know this is a query error, but I tried many things and I don't see the issue.
My query is this:
cm = new MySqlCommand("UPDATE customers SET first_name= " + txtNombre.Text + "," + " last_name= " + txtApellidos.Text + "," + " email= " + txtEmail.Text + "," + " phone= " + txtTelefono.Text + "," + " address= " + txtDireccion.Text + " WHERE id= " + dgvClient.SelectedRows[0].Cells[0].Value.ToString() , con);
There should be single quotes around the text that you want to inject into the query, so it will look like this:
var query = "UPDATE customers SET first_name= '" + txtNombre.Text + "'";
This is the easiest solution but is advised against, mostly because of a possiblity for 'sql injection'. The easiest way to show this is by using the name O'Brian, because of the quote the database will think that the name is only O and then see it followed by Brian that it doesn't know what to do with and gives an error. Some people can use this to add other things to your query to cause harm to your database (like dropping tables or the whole database)
It is advised to use parameters, this solves this whole sql injection issue. Your code will look as follows:
cm = new MySqlCommand("UPDATE customers SET first_name=#first_name, last_name=#apellidos WHERE id=#id", con) ;
cm.Parameters.AddWithValue("#first_name", txtNombre.Text);
cm.Parameters.AddWithValue("#apellidos", txtApellidos.Text);
cm.Parameters.AddWithValue("#id", dgvClient.SelectedRows[0].Cells[0].Value.ToString());
It is best to always use parameters for your query, you can also look into using a framework like Entity Framework that does this automatically for you.
Related
i am not getting what is the issue in the query probably i am not following the correct way to put the string and char sign , i am inserting the data in c# to local host with where clause please check the query and Error i am getting
Here is the query
String insertQuery = "insert into exam_add (id,session_id,Title,From_date,To_date,class_id,is_Post,is_Lock) select '"+id+ ",s.session,'" + title.Text+",'"+ from.Value.Date.ToString("yyyy-MM-dd")+",'"+to.Value.Date.ToString("yyyy-MM-dd")+ ", c.class_name,'"+x+",'"+x+" from year_session s, classes c where s.id = '1' and c.id='" + cls + "'";
Exception image
here the image for exception i am getting after run this query
On your ...'"+x+"... you forgot to close the single quotes. You open them but you never close them after you add the X variable to your query. All SQL is seeing is "'0," which is invalid syntax.
I recommend use SQLparameters to avoid sql injection but your error is you forgot to close the single quotes it shoud be like this '"+cls + "'
String insertQuery = "insert into exam_add (id,session_id,Title,From_date,To_date,class_id,is_Post,is_Lock) select '" + id + "','"+s.session+"','" + title.Text + "','" + from.Value.Date.ToString("yyyy-MM-dd") + "','" + to.Value.Date.ToString("yyyy-MM-dd")+"' , '"+c.class_name+"','" + x + "','" + x + "' from year_session s, classes c where s.id = '1' and c.id='" + cls + "'";
I don't know why you need that on select columns. and you provided insufficient information and code on your question.
Error Code : 1 (SQLITE_ERROR)
Caused By : SQL(query) error or missing database.
(near "=": syntax error (code 1): , while compiling: DELETE FROM notesWHEREid='1')
This is the error i am getting:
This is the part of my database handler that is the source of this error:
public void deleteNote(String id) {
SQLiteDatabase db = this.getWritableDatabase();
String deleteQuery="DELETE FROM " + DatabaseValues.TABLE_NOTES + "WHERE" + DatabaseValues.NOTES_ID + "= '" + id + "'";
db.execSQL(deleteQuery);
db.close();
}
If you are using C# 6.0, using interpolated strings makes life much easier for strings concatenation, avoiding such silly errors:
String deleteQuery= $"DELETE FROM {DatabaseValues.TABLE_NOTES} WHERE {DatabaseValues.NOTES_ID} = id";
Note: $ operator is available in C# 6.0. Also you should take a look into how to build parameterized queries because passing parameters like this can expose you to SQL injection.
Change your following statement:
String deleteQuery="DELETE FROM " + DatabaseValues.TABLE_NOTES + "WHERE" + DatabaseValues.NOTES_ID + "= '" + id + "'";
to
String deleteQuery= "DELETE FROM " + DatabaseValues.TABLE_NOTES + " WHERE " + DatabaseValues.NOTES_ID + " = '" + id + "'";
Actually you are combining the table name with where clause. You need to add a space before and after WHERE Clause like " Where "
Hope it helps.
So I have the following code :
public static void WriteToDatabase(string sql,string value,int Amount, string URL)
{
int times = int.Parse(((dr)[dt.Columns[1]]).ToString()) + Amount;
sql = "UPDATE Words "+
" SET Amount = " + times +
" WHERE Word = " + value +
" AND Website = " + URL + ";";
myAdp = new OleDbDataAdapter();
myAdp.InsertCommand = new OleDbCommand(sql, myConn);
myAdp.InsertCommand.ExecuteNonQuery();
}
Which supposed to update a value in a pre-made Microsoft Access 2007 file,
and whenever I run the code they following OleDb exception occurs :
An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll ,
Syntax error missing operator in query expression : 'Word = meta AND Website = http://www.twitch.tv/directory'."
"
So I've searched the web for common errors that could happen, and I couldn't find any,
I'll be glad if someone can find the mistake in the sql.
Thanks.
You absolutely should be using parameterized queries for this. That is the right way to pass values in.
Your problem is that your query is missing single quotes:
"UPDATE Words "+
" SET Amount = " + times +
" WHERE Word = '" + value + "'" +
" AND Website = '" + URL + "'"
But let me re-emphasize that although this should work, you should fix the code so it uses parameters
Assuming the Word field is a varchar, you have forgotten the necessary single quotes around the variable. " WHERE Word = '" + value + "'"
I am developing a program that uses a relational database. In one particular form I am trying to insert new products information into the database.
using System.Data.OleDb;
When I try to save a new product this code runs...
connection.Open();
OleDbCommand command = new OleDbCommand();
command.Connection = connection;
string query = "insert into Products (ProductName,ProductSKU,RP,WP,Stock,FPS,Ammo,MagazineCap,HopUp,Range,Brand,Colour,Action,Features) values('" + txt_ProductName.Text + "','" + txt_SKU.Text + "'," + txt_RP.Text + "," + txt_WP.Text + "," + numericUpDown_Inventory.Value + "," + cobo_FPS.Text + ",'" + cobo_Ammo.Text + "'," + cobo_MagazineCap.Text + ",'" + cobo_HopUp.Text + "'," + cobo_Range.Text + ",'" + cobo_Brand.Text + "','" + cobo_Colour.Text + "','" + cobo_Action.Text + "','" + txt_Features.Text + "')";
//Action field currently causes an error
MessageBox.Show(query);
command.CommandText = query;
command.ExecuteNonQuery();
connection.Close();
...and an error is thrown
"Error System.Data.OleDb.OleDbException (0x80040E14): Syntax error in
INSERT INTO statement."
(and then a bunch of stuff which I don't think is important)
Apologies for the HUGE SQL query. I am using the exact same method of using the insert SQL query in several other places in my program and they all work completely fine. This example however is causing this error. Through the tedious process of "commenting out" individual parts of my SQL query I found that the error lies with the "Action" field. I have checked that the data type in my database is correct and that I am using the '' punctuation to surround the text string that is being inserted into the database.
I think I've checked everything, so why am I still getting this error?
Many thanks in advance and if more information is required just let me know ;)
Action is a reserved keyword in OLE DB Provider. You need to use it with square brackets like [Action]. As a best practice, change it to non-reserved word.
But more impontant
You should always use parameterized queries. This kind of string concatenations are open for SQL Injection attacks.
Also use using statement to dispose your OleDbConnection and OleDbCommand automatically instead of calling .Close() method manually.
i got problem with a query, got something like this
command.CommandText = "SELECT " +
"COUNT(a.`id`) " +
"FROM " +
"`messageaccess` a " +
"WHERE " +
"a.`Users_LOGIN` = '" + Settings.UserLogin + "' " +
"AND a.`Status` = '" + Enums.MessageStatus.New + "' " +
"AND a.`FOLDER` = '" + Enums.MessageFolder.INBOX + "'" +
"AND a.`ShowAlert` = '" + Enums.YesNo.No + "'" +
"AND a.`Postponed` <= " + DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss") + "";
but sql throws me exception
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '14:40:37' at line 1
tried diffrent combinantions but nothing works :(
The simple answer is not to embed values directly into the SQL to start with.
Use a parameterized SQL statement, specify the parameter value as DateTime.Now, and all will be well:
Your SQL will be easier to read (as it'll just be the code, not the data)
You won't need to worry about formatting of things like numbers and dates
You won't be vulnerable to SQL injection attacks
You forgot the quotation marks around the date/time thing.
try using this line instead:
"AND a.`Postponed` <= NOW()"
and it should work with the native MySql function for the current time.
Have a look at named parameterized queries. They take care of these formatting issues for you.
You shouldn't build your query appending strings. This is not very safe (sql injection) and you're not taking advantage of the ADO .NET capabilities to set the correct format according the parameter type.
You should use parametrized queries.