This is not a question of working in IT or not. It is rather a question of style and good practice in (print) publishing or typesetting.
From a professional typesetting perspective (= How would this be set in a good book?) Datenbankmigration seems preferable because it supports fluent reading (no artificial stops inside the word).
However, Datenbank-Migration is a possible spelling, too.
Which to prefer - this depends on considerations such as is the audience accustomed to the word (then Datenbankmigration); an audience not familiar with the word may find Datenbankmigration a little bit difficult to read, and for such an audience it may be appropriate to put the hyphen in-between.
The scientific background is that reading with human eyes and brains is not like adding one letter to another (as a computer would) until something meaningful appears, but rather recognizing entire patterns at once such as a word or a cluster of words up to an entire line. Recognizing a pattern at once is like recognizing faces. For this type of reading Datenbankmigration is not a difficult mess of letters but a clear pattern that will be recognized instantly. But of course the reader must have the pattern stored in his brain in order to be able to recognize it.
For first-time readers, on the other hand, Datenbank-Migration will be more easy to de-cypher. (Requiring, of course, that at least the patterns Datenbank and Migration are available in the storage.)
Of course, most texts mentioning Datenbankmigration are written for people who know what that is, so Datenbankmigration will probably be more frequently met out there in the wild; or should be.
You could also say
Umzug der Datenbank
However, most IT people stick to their beloved English terminology, therefore Datenbankumzug (and derivatives) is rare.
 Think of type face here.