Relationships

..\sdk\sql.embedded\tutorials\eSQL_Tutorial2.pc

Now we will build some table/file relationships using the c-treeACE SQL ESQL - Embedded SQL Interface

This tutorial will advance the concepts introduced in the first tutorial by expanding the number of tables. We will define key columns/fields and create specific indices for each table to form a relational model database.

Like all other examples in the c-tree tutorial series, this tutorial simplifies the creation and use of a database into four simple steps: Initialize(), Define(), Manage(), and You’re Done() !

Tutorial #2: Relational Model and Indexing

Here we add a bit more complexity, introducing multiple tables, with related indices in order to form a simple "relational" database simulating an Order Entry system. Here is an overview of what will be created:

• Initialize() - Connects to the c-treeACE Database Engine.
• Define() - Defines and creates the "custmast", "custordr", "ordritem" and the "itemmast" tables/files with related indices.
• Manage() - Adds some related rows/records to all tables/files. Then queries the database.
• Done() - Disconnects from c-treeACE Database Engine.

Note our simple mainline:

/*

 * main()

 *

 * The main() function implements the concept of "init, define, manage

 * and you're done…"

 */

int main(int argc, char* argv[])

{

   Initialize();

   Define();

   Manage();

   Done();

   os_printf(DH_STRING_LITERAL("\nPress <ENTER> key to exit . . .\n"));

   getchar();

   return(0);

}

We suggest opening the source code with your own editor.

Continue now to review these four steps.