Sequences (PDM)

A sequence is like an advanced form of an auto-incremented column. Where the latter is a column whose values automatically increment by 1, sequences allow you to define more complex incrementations. Sequences are not supported by all DBMSs.

Once you define a sequence, you can apply and enable it to a column. The data type for the column receiving the sequence must be a numeric data type (see Selecting a Data Type for a Column). Such auto-incremented columns can be used in a key for a PDM table.

For example, if you want to create a column listing the months of the year (March, June, September, and December) when quarterly reports are published, you can define the proper sequence by entering the following values for sequence option parameters:

• Creating a Sequence
  You create a sequence from the List of Sequences and specify its physical options in the Physical Options tab ot its property sheet.
• Applying and Enabling a Sequence on a Column
  You apply a sequence to a column from the column property sheet and enable it using the Rebuild Triggers command.
• Sequence Properties
  To view or edit a sequence's properties, double-click its Browser or list entry. The property sheet tabs and fields listed here are those available by default, before any customization of the interface by you or an administrator.
• Changing the DBMS of a Model which Contains Sequences and Auto-incremented Columns
  If you create an auto-incremented column or a sequence attached to a column, and then decide to change the target DBMS various transformations will be effected.
• Sequences and Intermodel Generation
  When a CDM or an OOM is generated from a PDM, the data type of a table column attached to a sequence is translated to a numeric data type in the new model: