About maintaining columns on SQL tables

To add, delete, or modify columns on tables, use the Sql Columns form. However, understand that you cannot make changes to certain restricted tables.

Caution: 
You can add columns, but do not delete or modify columns on existing base application tables. Doing so can cause system instability.
Note: System administrators can use the Metadata Access Controls form to restrict access to core SQL tables. You cannot modify SQL tables that are set to Locked in the Metadata Access Controls form. You can view SQL tables that are set to Read Only but you cannot modify them. You can view and modify SQL tables that are set to Unlocked.

To add a new column to a table that already contains columns, the new column must meet at least one of these conditions:

  • Allows nulls
  • Has a default definition specified
  • Is an identity or timestamp data type

If none of these conditions is true, then the column can be added only to an empty table.

You can also change the definition of an existing column, for example, the data type.