TurboIMAGE/XL Database Management System Reference Manual MPE/iX V6.5 (30391-90011)
Chapter 3 65
Defining a Database
Item Part
Item Part
The item part defines data items including the data item name, length, and the user
classes that have access to the item. The data set(s) in which the data item appears is
defined in the set part definition.
Syntax
item name
, [
sub-item count
]
type designator
[
sub-item length
]
[(
read class list/write class list
)];
Parameters
item name is the data item name. It must be a valid TurboIMAGE/XL data name as
described earlier in Table 3-1.. It must be unique within the item part.
sub-item count is an integer from 1 to 255 that denotes the number of sub-items within an
item. If omitted, the sub-item-count equals one by default. A data item
whose sub-item count is 1 is a simple item. If the sub-item count is greater
than 1, it is a compound item.
type designator defines the form in which a sub-item value is represented in the computer.
The type designators E, I, J, K, P, R, U, X, and Z are described in Table 3-2.
in the section "Data Item Length."
sub-item length is an integer from 1 to 255. It is the number of halfwords, bytes, or nibbles
(depending on the type designator) in a sub-item. If omitted, it is equal to 1
by default.
read class list is a group of user class numbers between 0 and 63, inclusive, separated by
commas. User class numbers are described in chapter 2.
write class list is a group of user class numbers between 0 and 63, inclusive, separated by
commas. User class numbers are described in chapter 2.
Example
FIRST-NAME, X10 (12,14/11);
Description
There can be no more than 1023 data items in a database. A data item name can appear in
more than one data set definition. For example, a data item named ACCOUNT appears in
both the CUSTOMER and SALES data sets of the ORDERS database. The complete
ORDERS database schema appears at the end of this chapter.
Data Item Length
Each data item value is allotted a storage location whose length is equal to the product of
the item's sub-item length and its sub-item count. The unit of measure for the length