When using MySQL source table for CONNECT engine, VIRTUAL and PERSISTENT columns do not work as designed. The VIRTUAL column is required to be returned in the MySQL query result set or the table query fails.

For a VIRTUAL column, the work around is to ALIAS the column in the query with a supplied NULL value. When this is done, the CONNECT table works substituting the VIRTUAL calculation for the query supplied NULL. If ANY value other than NULL is specified in the source query, the specified ALIAS value takes precedence for the column value over the VIRTUAL calculated value.

Following the work around for a PERSISTENT column does not work at all. The NULL will take precedence over the Calculated value.

This was tested using a VarChar column definition.