In the -DH Lines tab, you can describe
the relationships between Segments in a hierarchical database, such
as DL/1.
Each line designates a Segment and its parent (except
for the line that refers to the root Segment). The description consists
of records and these records constitute the physical file.
This
description is common to the following IMS and DL/1 hierarchical Database
Block types:
- DP: Physical database description,
- DR: Physical database description (same
as DP, but only the Data Elements that are
referenced as access keys in the Segment description are generated
in the FIELD statements),
- DL: Logical database description,
- PC: PCB,
- IP: Primary index,
- IS: Secondary index.
The Comments column is displayed
only in the table of the tab. It does not correspond to a field of
the call line definition section. It contains an asterisk on the call
lines that have been assigned -G lines. These secondary-level -G lines
have been entered with the -G Lines button
in the call line definition section. If you hover your cursor on the
asterisk, the -G lines of the call line are displayed in a tooltip.
If you click the button that is associated with the asterisk, the
-G lines are displayed in their tabular editor, where you can modify
them. You can also display and modify the -G lines from the Edit
comments choice in the contextual menu of the call line.
-DH lines definition
The -DH
lines definition section is displayed when you enter
or click a description line. In this section, you can enter information
about the description line.
- Definition
- The Block code field is active only for PS-type
Blocks. To select PSB Database Block, you must click Change.
The dialog box that opens lists the available PSB databases. The code
of the selected database is displayed as a link that automatically
switches to the Database Block editor.
- For a PSB database called on a -DH line, you must enter only the Key
indicator or option and Comment/relationship/key
length fields.
The following Segment options are active for all
Block types other than the PC or PS type.
- Segments
- Select the Segment code. SOCRATE/CLIO database: Select the code
of the Segment, which is used to generate the entity, the formal or
the SOCRATE/CLIO Segment. To enter or modify the contents of this
field, click Change. In the dialog box that
opens, you can select a Segment in the list of the available Segments.
If the list is large, you can reduce it by entering a string that
is used as filter (the filtering is performed on the code or on the
label of the instance).
- Parent Segment
- Click Change to select the code of the
Segment that the given Segment is hierarchically dependent on. This
field is not used forIP or IS-type
Database Blocks.
- Relation code
- This field is optional. It is used only if the type of Block
is PSB to name the different DBD and PCB called.
- Key indicator or Option
- Enter the key indicator that is used as the symbolic reference
of the key Data Element of a Segment in a Database Block. The character
that is indicated in this field must also be entered in the -CE
Lines of the Segment, in the Sort key field
of the Data Element call line.
- In this field, you can enter the following values:
- U to indicate a unique key,
- M to indicate a multiple key
- A digit between 1 and 9 to
indicate a DL/1 Secondary index,
- $ in a PCB or a physical or logical DBD,
if you want to generate a non-qualified SSA,
- Any other values to indicate a search field.
Note: Key indicators are not permitted on Data Elements that
are used to redefine other Data Elements.
- Estimated number of links
- Enter the average number of occurrences of a child Segment that
is linked to one occurrence of its parent Segment.
- Comment/Relationship/Key length
- You can use this field to document the defined parent-child link.
You can also use it to indicate the concatenated key length.
- When generating PS-type Database Blocks
(a PSB), the length of the longest concatenated key is automatically
calculated for each of the following elements:
- A DBD called in a PSB,
- A PCB called in a PSB,
- An index database that is called as an independent database in
the PSB.
- You can override his length by entering the following characters
on the first line: CC=n (with n = 9 - 9999).
- On each Segment call line, you can enter PR=nnnn to
generate the PROCOPT=nnnn parameter in the SENSEG statement
when generating the PSB, which contains this DBD, PCB, or index database.
Note: The length is calculated only for a primary Segment. In
the case of a secondary index, the CC= parameter is
required.
- -G Lines
- This button can be used to access the -G Lines wizard
and create -GG lines that are associated with the description line.
On these lines you can enter or modify information to complete the
description line before the generation.