C # Write database operations!

For some reason, the database software on which the software depends will change! If the opening and operation code of the database appear on each page, it will be quite troublesome to modify the code after the database software is changed. Therefore, writing database operation code into a class will not cause the above situation and reduce the amount of code. Source code
Using System;
Using System. Data;
Using System. Data. SqlClient;
Namespace news. common
{
/**
*-----------------
* Database connection/Operation
* Create
* Ryan_bin@126.com
*----------------
*/
Public class DBClass
{
/* ---- Global variable definition ------*/
Private SqlConnection conn;
Private SqlCommand comm;
Public SqlDataReader dr;
Public DataSet ds;
Public SqlDataAdapter dad;
Private string SQL;
Private string connStr;/* database connection string */
Private string errInfo = "";
/*----------------------*/