Pathmaker Programming Guide

Creating a DB Requester Application
Pathmaker Application Development Overview
3–30 067868 Tandem Computers Incorporated
Restrictions for DB
Requester Applications
Accessing NonStop SQL
Databases
Restrictions for NonStop SQL DB requester applications are:
You cannot use a shorthand view in a DB requester.
NonStop SQL tables in a Pathmaker DB requester can only be linked on a single
column.
If you use a protection view, the view must include every column of the primary
key or of a unique index. You cannot access a protection view from a SQL DB
requester whose only column is a SYSKEY. You cannot insert into a nested
protection view whose link field is a SYSKEY.
Note that for a protection view that uses a clustering key, the primary key consists
of the columns of the clustering key plus a SYSKEY.
You cannot display the SYSKEY on a base table.
If you want to display the SYSKEY, you can create a protection view that
specifically includes a column name for the SYSKEY.
You cannot preserve trailing blanks on a variable-length character column
(VARCHAR) when you update it.
If you have a VARCHAR declared in your table, the SQL standard server
automatically trims trailing blanks when you update the column.
The SQL standard server is limited to accessing about 100 tables, although this
limit varies depending on the size of the table descriptions in the Working-Storage
Section of the server.
The SQL standard server improves the application’s performance by caching 100
of the most commonly used queries in precompiled form.
You cannot use the SQL standard server to update a key on a view. You must
update keys on a base table.
If you disallow nonindex reads, the link column of the child must be a primary
key or index or the first column of a multicolumn primary key or index. To
disallow nonindex reads, you place an N in the Nonindex Reads field of the Record
Instance Detail screen and press F2 to update the screen.
You cannot delete a row from an entry-sequenced file.
NonStop SQL allows keys to be defined in ascending or decending order. When
you read a table using a DB requester, however, the rows are retrieved in
ascending order.