When developing web applications an infraestructure to access the database is needed. In other words, a piece to connect the bussines logic to the database, to invoke the stored procedures (SP) that works with data. This layer has to be easy to work with, automated at maximum to avoid messing with the boring task of building the parameter list of the SPs by hand (a process also prone to errors). For this reason I've build the clsData.

clsData is the principal class of the data layer, it holds all of the methods to acces the database. It invokes the SPs, but as every SP has different parameters, other clases creates the definition for those parameters and inherite from clsData to add the methods to invoke the SPs.

So, clsData has the methods to acces and other clases that use inheritance has the definition needed to fill the methods of clsData. For this reason clsData has the declaration of the variables that later the other classes will initialize with the correct values. Those variables, in fact, are lists of objects that has information to build a SQL parameter. First of all I use a simple class to store type information (and when I say type I'm refering to database type), the DBType class.

    public static class DBType
    {
        public const int bit = 1;
        public const int tint = 2;
        public const int bigint = 3;
        public const int nvarchar = 4;
        public const int datetime = 5;
        public const int nchar = 6;
        public const int dec = 7;
        public const int varchar = 8;
        public const int chr = 9;
        public const int date = 10;
        public const int time = 11;
    }

There's also a class that describes a datatable column (that generates a SP parameter of the same type and name): clsColumn

    public class clsColumn
    {
        public string ColName= "";
        public bool Nullable = true;
        public int DB_Type;
        public string Format = "";
        public int Len = 0;
        public bool PK = false;
        public bool Identity = false;
        public byte Precision = 0;
        public byte Scale = 0;
    }

From now on, I will describe with more detail all the variables involved in the class clsData, and its inner workings.