Alteryx to SQL - Dynamic schema

Hi All,

I am outputting data from an excel spreadsheet to a SQL table on Alteryx. The challenge I am facing is that the schema changes periodically as I would have additional columns on my excel spreadsheet. Due to this my Alteryx workflow fails to write the data to SQL table. What is the best way to do it ?

Table on week 1

Name	Age
ABC	12

Table on week 2

Name	Age	Gender
ABC	12
DEF	14	Male

Developer

Accepted answers

All comments

OTrieger

@Mario36

Just add a Select tool and mark the needed fields, and then untick the Unknown so new fields will not be active.

Mario36

I don't think that would help. I need my previous schema to be intact and append the new schema.

alexnajm

Since you are changing the schema, you should probably look at the Drop Table option so you can have the new schema. That means though that you have to read it as an input first, union the data together, and THEN drop and reload the table

alexnajm

@Mario36 any luck?

Mario36

Its duplicating the entry

This is what I get :

Name	Age	Gender
ABC	12
ABC	12
DEF	14	Male

This is what I want

Name	Age	Gender
ABC	12
DEF	14	Male

What I have given is an example but in actual I have an existing table with millions of rows.

alexnajm

That doesn't make sense though - if you've dropped the entire table then there would be no data leftover. Do you have the correct permissions to drop tables? Is your Union logic correct? You'll have to give us more information

Otherwise you'll have to do some sort of Alter Schema statement as a Pre SQL and figure out how to dynamically pass the new columns in to alter the structure beforehand

Mario36

What's the option you are suggesting to use on the Output data tool, 'Overwrite Table(Drop) ?
I do have permissions. What additional information is required ?

alexnajm

I'm not sure what you mean - it's a setting in your Output Data tool

Screenshot 2026-03-26 123857.png

Mario36

Perfect, so the problem seems to be in the way the Union is happening.

alexnajm

I agree!

Mario36

Is there a better way to do it ?
I either have to first read the existing table > store to a temp file like a yxdb > Union the new table with the old table > Drop and overwrite the new appended table

alexnajm

Because of your requirement to change the schema every time (the columns), I don’t see another way besides using pre SQL in the output data tool. You’ll run into errors from SQL otherwise

I don’t have any more suggestions beyond this unfortunately, so If there’s more you’ll have to provide a workflow or something more substantial for us to advise on, but please try the solution and if there’s an error or something, then we can help further. Good luck!

jrlindem

I'm not sure, as @alexnajm points out, that there is a way to accomplish what you need dynamically. Meaning, a complete way to future-proof schema changes. You'll likely have to perform some manual maintenance to the workflow whenever you detect a change in the schema of your new data.

If and when that happens, you'll need to make modifications. If you need to be made aware of when this occurs (say your workflow is scheduled on gallery) then you could get creative and use the Field Info Tool to do a comparison of the fields in the Database Object and your Input Data. If you want to push that a step further, you could consider putting that comparison into some logic, and then having different outputs occur using Control Containers.

Meaning, if the fields are the same, produce a single "TRUE" result that flows into one Control Container that runs your ETL job. If there are differences, then it goes to a different Control Container and sends you an email notifying you of the difference and the need for maintenance.

Check out this article and it will help you: Tool Mastery | Control Container - Alteryx Community

Refer to the "Conditional Execution" section.

Hope this helps provide some additional things to think about that could be useful, -Jay

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