Rational Programming Patterns for System z

Defining description lines in a Database Block

The tab dedicated to the description lines is specific to the type of Database Block that has been defined in the Database Block editor. You find the -DH Lines tab, which is specific to the hierarchical Database Blocks, the -DR Lines tab specific to the relational Database Blocks and the -DC Lines tab dedicated to the CODASYL, DMSII and TANDEM Database Blocks.

About this task

What are the description lines used for? The procedure to create description lines is the same for all Database Block types. In the tab dedicated to the description lines of a Block, you can specify the description lines of the current Block in a tree structure list. You can also delete some of them, reorganize them in the list. The other part of the window displays definition sections that open when you select a description line in the list. In these sections, you can give further information about the selected description line. Moreover, in the -GG lines section, you can specify generation elements associated with the selected description line too.

Procedure

  1. To create a -DC line, click the Add -DC line button. As a result, a default A: area, line is created in the list. You can change the line type in the -DC lines definition section displayed in the second part of the tab and you can create -GG lines associated with the -DC line by using templates in the -GG lines section.
  2. To create a -DH line, click the Add -DH line button. As a result, a default -dh line is created in the list. In the -DH lines definition section, when you select a Segment, parent Segment or child Segment for the generation of the description line, the Segments name is displayed in the list and identifies the description line. You can create generation elements for the -DH line in the -GG lines section.
  3. In the -DR line tab, you can create -DR lines that display the objects type, external names, the code of the Segments which represent them, and K-type lines which represent the key type supported by the Segment and the generation code.
    1. To create a -DR line, click the Add –DR line button. A default P: table space, line is created. You can change the type of SQL record in the -DR lines definition section displayed in the second part of the tab. The external name followed by the table or view code specified in this section are instantly displayed in the list to identify the description line. You can then add -GG lines to modify the -DR line in the -GG lines section.
    2. In the -GG lines section, you find a table with 'templates' that help you specify generation elements for the selected -DR line.
    3. You can create -K lines (K for keys) under a line that describes an SQL record and whose type is index, alter table or primary key. To do so, click the description line under which the -K line is to be created, then click the Add -DR –-K line button. As a result, a default Unknown: (no order) line is created in the list. In the -K line definition section displayed at the bottom of the tab, you can specify the composition of the Segment which represents the SQL record (index, alter table or table key). The Data Element and order type you have selected for the key are then displayed in the list to identify the description line.

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