front end: Visual Basic C# 2019;
back end: SQL Server 2017;

I am rather new to C# and could use some help. I am reading a SQL table using a SQL data reader. Here is the code

Code:
string strSQL = "select * from proddta.f4311 where pdan8='" + supplierNo + "' AND PDDRQJ>='" + jdeStart + "' AND PDDRQJ<='" + jdeEnd + "' order by pddrqj";
SqlConnection con = new
...