Encryption of Data in Appian SQL to Excel

We have an requirement to store the encrypted values in our Application DB. In such case we end up with storing encrypted data in couple of the tables. 

The Applications use SQL to Excel smart service in few reports. Here is what the challenge we have and required you guys idea's

1. If SQL to Excel smart service runs at back-end output will be Excel File (document)
2. On execution it will fetch data directly from tables whether it is normal or encrypted
3. In our case if any execution of this smart service runs on the table which has encrypted data, the output document will have the encrypted data
4. Its not like that entire table columns will have encrypted value, but few columns
5. If we send the document over an email to any users the file will have encrypted data which is not required

Is there any best way to Decrypt the data in this case ???

• It's SQL to Excel and hence number of rows exceeds 50k or even more than 1M rows