SQL20478 error when you run a query

If a data masking rule applies to TableA and you run a query that uses CREATE TABLE ... AS SELECT ... FROM TableA, you might see an error message with Reason code "30". SQLCODE=-20478, SQLSTATE=428HD.

Symptoms

This error occurs because by default, masked data cannot be written to tables or transition-variables. For example, you might see the following error message.

The statement failed because the column mask "EXTERNAL.Transform" defined for column 
"SCHEMA.TABLE_NAME.COLUMN" exists and the column mask cannot be applied or the column mask 
conflicts with the failed statement. Reason code "30". SQLCODE=-20478, SQLSTATE=428HD

Resolving the problem

To allow writing of masked data, set the DB2_ALLOW_WRITE_OF_MASKED_DATA registry variable to YES.

Log in to the Data Virtualization head pod.
```
oc rsh c-db2u-dv-db2u-0 bash
```
Switch to the Data Virtualization database instance owner db2inst1.
```
su - db2inst1
```
Test the connection to the Big SQL database.
```
db2 connect to bigsql
```
Set the DB2_ALLOW_WRITE_OF_MASKED_DATA registry variable to YES.
```
db2set DB2_ALLOW_WRITE_OF_MASKED_DATA=yes -immediate
```
Changes to this variable can take effect immediately for all future compiled SQL statements if the db2set command is issued with the -immediate parameter. You do not need to restart the instance.