c# - 使用datagridview更新数据库中的数据

Question

我有这样的代码:

public int updateFriend(long id, string Firstname, string Lastname, string Nickname, DateTime Birthdate, int Age, string Gender)
    {
        OleDbConnection con = new OleDbConnection(conString());

        string query = "UPDATE FriendList SET Firstname  ='" + Firstname + "', Lastname ='" + Lastname + "',Nickname ='" + Nickname + "',Birthday ='" + Birthdate + "',Age ='" + Age + "', Gender  ='" + Gender + "' WHERE ID = " + id;

        OleDbCommand cmd = new OleDbCommand(query, con);

        con.Open();

        int rowsAffected = cmd.ExecuteNonQuery();
        con.Close();

        return (rowsAffected);
    }

现在的问题是，当我单击更新按钮时，它会调用方法 updateFriend，然后在行 "int rowsAffected = cmd.ExecuteNonQuery(); 上出现错误"说

"No value given for one or more required parameters."

有人可以帮我解决这个问题吗？

Answer 1

string query = "UPDATE FriendList SET Firstname  ='" + Firstname + "', Lastname ='" + Lastname + "',Nickname ='" + Nickname + "',Birthday ='" + Birthdate + "',Age ='" + Age + "', Gender  ='" + Gender + "' WHERE ID = " + id;

您将所有参数作为字符串传递，其中一些是 int，一个是 DateTime。根据建议，您应该使用 Parameters.AddWithValue()

string query = "UPDATE FriendList SET Firstname = @Firstname, Lastname = @Lastname , Nickname = @Nickname, Birthday = @Birthdate, Age = @Age, Gender = @Gender WHERE ID = @id";
SqlCommand cmd = new SqlCommand(query, con);
cmd.Parameters.AddWithValue("@Firstname", FirstName);
//add rest parameters the same way as above
cmd.Parameters.AddWithValue("@id", id);