Database table selector and credentials

Hi guys

I created a wrapped metanode in order to give the possibility to connect to different internal databases and I plan to share it using the knime server features.

In this metanode you have 2 quickforms where you have to specify the database source and your username/password using credentials input.

Using those two user inputs, the database url and the authentification fields of the "Database connector" node are filled.

This metanode has only one output a database connection and it works.


But if I want to connect a "database table selector" to this metanode, I got an error message.

Execute failed: Error while validating SQL query: No credentials stored to name "databaseCredentials" (databaseCredentials is my flowvariable). 

For your information, I got this error message only if the "database table selector" is outside the metanode.

What should I do ?




Hi Joel,

first of all thanks for the detailed description which made it easy for me to reproduce your issue.

To get it running you have to configure the "WrappedNode Output" node within the metanode such that your credential-variable is visible outside the wrapped metanode.

This is because if your MySQL Connector is saved in an executed state and you reopen the workflow, the Database Table Selector needs the information to create the DB connection itself. Little confusing and probably gets reworked somewhen, but for now the solution above should work out for you.


Hi Marten

Thanks for your reply.

I did'nt know that I have to configure the output of a wrapped node, so I looked in the forum and I found this post

Like Luuklag, I always open a wrapped metanode using the double click and note the open option.

Now it works, thanks again.