I am migrating existing data in to a Skyve application. The existing application has an auto generated number to identify the "request".
I found this : https://skyvers.github.io/skyve-dev-guide/utility-classes/#document-number-pattern
But how do I set an initial value?
You put an initial value into the corresponding record in admin.DocumentNumber document (ADM_DocumentName table). You can either do this with an SQL insert as part of a deployment script or a manual deployment step through the admin module user interface (Admin->DocumentNumbers menu item)
If there is no DocumentNumber entry for the module/document/attribute combination, Skyve will create an entry starting at 1.
You can use something like
insert into ADM_DocumentNumber (bizId, bizVersion, bizLock, bizCustomer, bizDataGroupId, bizUserId, bizKey, moduleName, documentName, sequenceName, documentNumber)
VALUES (lower(newId()), 0, '20220714000000000admin', '<customer-name>', NULL, '<bizIdOf_ADM_SecurityUser>', '<module-name>.<document-name>.<attributeName>', '<module-name>', '<document-name>', '<attribute-name>', (select max(<legacy-column>) from <legacy-table>));