Convert Datatypes

You can convert only datatypes that are either implicitly or explicitly convertible to the new datatype, or if there is an explicit conversion function in Transact-SQL.

See, System and User-Defined Datatypes, in the Reference Manual: Building Blocks for a list of the supported datatype conversions. If you attempt an illegal datatype modification, SAP ASE raises an error message and the operation is aborted.

Note: You cannot convert an existing column datatype to the timestamp datatype, nor can you modify a column that uses the timestamp datatype to any other datatype.

If you issue the same alter table...modify command more than once, SAP ASE issues a message similar to this:

Warning: ALTER TABLE operation did not affect column ‘au_lname’.
Msg 13905, Level 16, State 1:
Server ‘SAP1’, Line 1:
Warning: no columns to drop, add or modify. ALTER TABLE ‘authors’ was aborted.