Using ModelBuilder to select layers by attributes, dissolve and then merge them?

Question

I would like to reclassify polygons, I want to combine smaller polygons into bigger polygons based on their ID (each polygon has a unique ID). I want to regroup ~800 polygons into ~60 polygons. So in the first round I, e.g, want to select polygons with the ID 3,5,7 and dissolve them into one. In the second round I want to select polygons with the ID 34,666, 45,6,77 and dissolve them...until all the polygons are regrouped and dissolved. Then I would like to merge all the dissolved polygons into a new shapefile with only ~60 polygons.

So I thought I can automate this with the ModelBuilder, first I tried an approach with

Make Feature Layer then Select by Attributes then Dissolve. But that way I still have to change the SQL statement in the Select Layer By Attribute each time. Also I wouldn't know how to save the dissolved output layer after each run so that it doesn't overwrite it. Is there a function that keeps merging the previous model output with the current output?

While searching for solutions online I came across the Feature Class to Feature Class option as it apparently makes the Make Feature Layer and Select Layer By Attribute steps unnecessary. How could I then use a list variable of SQL statements and a list variable of string names for the different outputs as input?

Answer 1

Consider the following workflow:

1. Add Field to polygon feature class
2. Calculate field (See attached Code Block)
3. Dissolve based on your new reclassified field values (i.e. 1 or 2)

Hopefully this simplified approach, or a variation of it, will work for you.

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