Guidelines for Adding an Extension Column to a Base Table

You can add an extension column to a predefined base table. Adding an extension column avoids having to add another join to an extension table to store custom data. You can add an extension column to any of the following table types:

• Data table

• Intersection table

• Interface table

• Predefined extension table

• Custom extension table

• Extension (Siebel) table

You cannot add an extension column to a private data table that contains a value of Data (Private) in the Type property. Some interface tables are private, but most are public. Use the following guidelines if you add a column to a table:

• Any column you add must conform to the data type limitations of all the RDBMS types that your enterprise uses. Consider your server database and any regional or remote databases.

• If you add a new column to a predefined table with one or more rows of data, then the RDBMS does not allow you to add the column unless you include a default value.

• You cannot remove a column after you add it to a table. For more information, see the documentation for your database technology.

• If you add a column to a table, then do not use a column name that includes a word that is reserved on your server or client database. If you use an underscore (_) at the beginning and end of the reserved word, then you can use a reserved word. For more information, see Naming Format for a Siebel Table.

• If you create a new extension column in the Siebel schema, then padding problems might occur with Siebel Remote. For more information, see Siebel Remote and Replication Manager Administration Guide.