For systematic and scoping reviews you must search multiple databases. At a minumum:
plus at least two of...
You should also consider:
Searches should be saved for each database so that search strategies can be reproduced in the final report. Records should also be kept of when key searches were carried out.
In order to be as comprehensive as possible it is recommended that searches are as broad as possible with inclusion or exclusion decided at the screening stage. Tightly targeted searches risk failing to identify relevant papers.