For ArcGIS to work with multiple data types, certain characters in field or table names are not supported. These characters include spaces, hyphens, such as in the term 'x-coord', brackets, and other special characters. These limits are imposed so that ArcGIS is able to function with the maximum amount of data types.
The limit for the length of field and table names depends on the underlying database management system (DBMS). Consult the DBMS documentation for information on naming limits for a particular DBMS. A dBASE field name can be up to 10 characters long, and there is no limit on the length of the table name.
Note: Microsoft SQL Server databases named with a number at the beginning are also not supported.