How to insert,delete,select,update values in datagridview in C# using MYSQL

Answer 1

I think you need to change the names of the parameters added to the insert command to match the names specified in the INSERT SQL statement.

Try:

insertcommand.Parameters.Add("@username",MySqlDbType.VarChar,50,"username");
insertcommand.Parameters.Add("@password", MySqlDbType.VarChar, 50, "password");

Answer 2

I am rather unsure, but doesn't mysql use numbered parameters with a "?"-synatx or named parameters with a ":"-syntax instead of (mssql) at-syntax ?

Something like :

MySqlCommand insertcommand = new MySqlCommand("insert into user(username,password) values(?, ?)", conn);
insertcommand.Parameters.Add(1, MySqlDbType.VarChar,50,"username");
insertcommand.Parameters.Add(2, MySqlDbType.VarChar, 50, "password");

or

MySqlCommand insertcommand = new MySqlCommand("insert into user(username,password) values(:username, :pass)", conn);
insertcommand.Parameters.Add(":username", MySqlDbType.VarChar,50,"username");
insertcommand.Parameters.Add(":pass", MySqlDbType.VarChar, 50, "password");