C# SQL klasse

Hej Udviklere,

jeg er i gang med at udvikle min egenklasse, som skal varetage kommunikation med SQL Server 2005 i mine projekter (skole projekter). Klassen ser ud som følgende:

 using System;
 using System.Collections.Generic;
 using System.Data;
 using System.Data.Sql;
 using System.Data.SqlClient;
 
 namespace Mssql
 {
     public class SqlClass
     {
         static SqlClass instance = null;
 
         DataTable dTable = null;
         SqlDataAdapter sqlAdapter = null;
         SqlConnection connection = null;
 
         private SqlClass()
         {
             connection = new SqlConnection();
         }
 
         public int NonQuery(string query)
         {
             SqlCommand sqlCommand = this.connection.CreateCommand();
             sqlCommand.CommandType = CommandType.Text;
             sqlCommand.CommandText = query;
 
             return sqlCommand.ExecuteNonQuery();
         }
 
         public string Close()
         {
             this.connection.Close();
 
             return connection.State.ToString();
         }
 
         public string Open()
         {
             this.connection.Open();
 
             return connection.State.ToString();
         }
 
         public string[,] ToArray()
         {
             string[,] data = new string[this.Columns, this.Rows];
 
             for(int i = 0; i < this.Columns; i++)
             {
                 for(int j = 0; j < this.Rows; j++)
                 {
                     data[i, j] = this.dTable.Rows[i][j].ToString();
                 }
             }
 
             return data;
         }
 
         public void Query(string query)
         {
             SqlCommand sqlCommand = this.connection.CreateCommand();
             sqlCommand.CommandType = CommandType.Text;
             sqlCommand.CommandText = query;
 
             this.dTable = new DataTable();
             this.sqlAdapter = new SqlDataAdapter(sqlCommand);
             this.sqlAdapter.Fill(this.dTable);
         }
 
         public void SetInfo(string dataSource, string catalog)
         {
             string connString = "Data Source=" + dataSource + "; Initial Catalog=" + catalog + "; Integrated Security=SSPI;";
 
             this.connection.ConnectionString = connString;
         }
 
         public void SetInfo(string dataSource, string catalog, string userId, string password)
         {
             string connString = "Data Source=" + dataSource + "; Initial Catalog=" + catalog + "; User ID=" + userId + "; Password=" + password + ";";
 
             this.connection.ConnectionString = connString;
         }
 
         public void StoredProcedure(string procedure, string[,] parameters)
         {
             SqlCommand sqlCommand = this.connection.CreateCommand();
             sqlCommand.CommandType = CommandType.StoredProcedure;
             sqlCommand.CommandText = procedure;
 
             for (int i = 0; i < parameters.GetLength(0); i++)
             {
                 SqlParameter sqlParam = new SqlParameter("@" + parameters[i, 0], parameters[i, 1]);
                 sqlCommand.Parameters.Add(sqlParam);
             }
 
             this.dTable = new DataTable();
             this.sqlAdapter = new SqlDataAdapter(sqlCommand);
             this.sqlAdapter.Fill(this.dTable);
         }
 
         public DataTable Fetch()
         {
             return this.dTable;
         }
 
         public static SqlClass getInstance()
         {
             if (instance == null)
                 instance = new SqlClass();
             return instance;
         }
 
         public int Columns
         {
             get
             {
                 return this.dTable.Columns.Count;
             }
         }
 
         public int Rows
         {
             get
             {
                 return this.dTable.Rows.Count;
             }
         }
     }
 }

Jeg har ikke lavet specifikke funktioer, som laver en "select" eller "update" som man kender i nogle frameworks (codeigniter til php).

Spørgsmålet går nu på, er der noget som I mener jeg mangler i klassen for at gøre den mere "komplet"? Desuden så er jeg ikke helt sikker på hvordan jeg skal fange OUT parametere i Stored Procedures, men vil min nuværende metode kunne dette?