Database management systems and cloud data warehouses have different definitions of acceptable characters for object names. Most allow you to use unacceptable characters if you provide the object name enclosed in delimiters, such as double quotation marks.
However, ArcGIS does not add delimiters when querying objects in the database. Do not create any tables, feature classes, indexes, databases, users, roles, or other object names that require delimiters if you will use them with ArcGIS. The object will be created in the database, but you cannot access it from ArcGIS.
Similarly, delimiters are not added when you create database objects, such as a table or database, from ArcGIS. If the name you provide when you create the object uses character casing that the database does not support unless the text is inside delimiters, the underlying database changes the casing. This could result in you receiving an error message indicating the object does not exist the next time you attempt to access the object.
Note:
Microsoft SQL Server usernames containing special characters are delimited to fully support Windows Active Directory Groups and Windows Authenticated logins; however, ArcGIS does not support usernames containing single quotation marks or apostrophes.