How to pass in the username, password, and id as parameters into a query ?

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Is there anyway i can pass in the username, password, and id as parameters
into a query ?

I created a method to do that:

and tried to call it

this.Update("jen", "779", "55") ;

but i am getting :

C#

An unhandled exception of type 'MySql.Data.MySqlClient.MySqlException' occurred in MySql.Data.dll

Additional information: Unknown column 'user' in 'where clause'

at the line

C#

cmd.ExecuteNonQuery();

C#

public void Update(string user, string passw, string ID)
     {


         string query = "UPDATE users SET username= user, password= passw, id= ID  WHERE username= user";

       //string query = "UPDATE users SET username='Joe', password='22', id='33'  WHERE username='Joe'";

 //Open connection
 if (OpenConnection() == true)
 {
     //create mysql command
     MySqlCommand cmd = new MySqlCommand();
     //Assign the query using CommandText
     cmd.CommandText = query;
     //Assign the connection using Connection
     cmd.Connection = connection;

     //Execute query
     cmd.ExecuteNonQuery();

     //close connection
     this.CloseConnection();
 }



     }

What I have tried:

*--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Posted 5-Nov-16 23:46pm

forte74

Updated 6-Nov-16 2:24am

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Midi_Mick · Answer 1 · 2016-11-06T00:04:00

There are 2 things amiss here.

Normally (depending on which database engine you're using), parameter names are prefixed in the query string with an "@". It looks like you're MySQL there, and this is the case for that database engine. This means your query becomes

SQL
```
UPDATE users SET username= @user, password= @passw, id= @ID WHERE username= @user
```

You need to add the parameters to the DbCommand object

C#

cmd.Parameters.AddWithValue("@user", user);
cmd.Parameters.AddWithValue("@passw", passw);
cmd.Parameters.AddWithValue("@ID", ID);
...
cmd.ExecuteNonQuery();

W∴ Balboos, *GHB* · Answer 2 · 2016-11-06T02:24:00

Your query string is incorrect. Why?
Because

username= user

is sent to the server exactly as you enter it. 'user' is not replaced by its value and is consider, in fact, a column name in many version of sql.

You need to build the string so that the values are substituted in the string. For example,

username='{0}'

in your string, where user is it's value. For the rest of how to use this, see See C# string functions.

Remember to include single quotes around strings. on the format side of your string as you need them passed to the sql execution.

How to pass in the username, password, and id as parameters into a query ?

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