You should use two or more databases so that you reduce the risk of missing relevant articles. Combining several databases also reduces the risk of bias in the results. Select relevant subject-specific databases and supplement them with an interdisciplinary database, such as Web of Science or Scopus.
It is not possible to use the exact same search in every database – searches must be adapted to each database. For example, special characters can be interpreted differently by different databases. In general, it is best to start with the database that has the most sophisticated indexing and then “translate” the search to the remaining databases.
Although you need to modify the search for it to work in different databases, do not change the search unless necessary. The different searches should correspond to each other as much as possible.