C# mysql database connection class object error

Question

Im new to C# and I just create a database connection using mysql. Then I need to define a database connection class here this is my code

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using MySql.Data.MySqlClient; namespace restsurant_pos { class mysqlDbConnect { public static MySqlConnection GetConnection(){ string MyConnectionString = "Server=Localhost;Database=pos;Uid=root;Pwd='';"; MySqlConnection connection = new MySqlConnection(MyConnectionString); MySqlCommand cmd; connection.Open(); return connection; }

hope it is correct..

then how can I create a object using this class. I just created a as below, but it is getting an error.

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; using MySql.Data.MySqlClient; namespace restsurant_pos { public partial class AddCategory : Form { public AddCategory() { InitializeComponent(); } private void btn_insertCategory_Click(object sender, EventArgs e) { string categoryName = txtCategoryName.Text; mysqlDbConnect connection = new mysqlDbConnect(); try { cmd = connection.CreateCommand(); cmd.CommandText = "INSERT INTO categories(name) VALUES(@categoryName)"; cmd.Parameters.AddWithValue("categoryName", txtCategoryName.Text); cmd.ExecuteNonQuery(); this.Close(); } catch (Exception) { throw; } finally { if (connection.State == ConnectionState.Open) { connection.Close(); } } } } }

what is the wrong with my code.. pls help

It looks like you haven't defined cmd. Try putting var or MySqlConnection in front of it — user4189129
– user4189129, Commented Nov 17, 2016 at 12:11

James Gould · Accepted Answer · 2016-11-17 12:11:32Z

2

You haven't providing a type for cmd.

Solve it by declaring it (lazily) as var cmd = connection.CreateCommand() or use a hard coded type.

answered Nov 17, 2016 at 12:11

James Gould

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7 Comments

KBK Over a year ago

yes cmd solved... but connection.CreateCommand(); ,connection.State and connection.Close(); still remaining...

James Gould Over a year ago

you need to use connection.Open(). Right now you've created a connection, but not opened it.

James Gould Over a year ago

also, "still remaining" isn't exactly descriptive. What are the errors..?

KBK Over a year ago

Error	2	'restsurant_pos.mysqlDbConnect' does not contain a definition for 'CreateCommand' and no extension method 'CreateCommand' accepting a first argument of type 'restsurant_pos.mysqlDbConnect' could be found (are you missing a using directive or an assembly reference?)	C:\vb\restsurant_pos\restsurant_pos\AddCategory.cs	29	38	restsurant_pos

KBK Over a year ago

Error	3	'restsurant_pos.mysqlDbConnect' does not contain a definition for 'State' and no extension method 'State' accepting a first argument of type 'restsurant_pos.mysqlDbConnect' could be found (are you missing a using directive or an assembly reference?)	C:\vb\restsurant_pos\restsurant_pos\AddCategory.cs	42	32	restsurant_pos

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