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Editorial Team
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Asked: 2026-06-17T19:53:40+00:00

I have a table: INSTRUCTIONS: RecipeID Step … RecipeID is generated by another system.

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I have a table:

INSTRUCTIONS:
  RecipeID
  Step
  ...

RecipeID is generated by another system. There does not need to be an explicit foreign key relation for RecipeID. As I insert steps into Instructions for a particular recipe, I would like Step to increment. When adding steps to a new recipe step should be back at 0 like so:

RecipeID | Step
---------------
    0    |  0
    0    |  1

RecipeID | Step
---------------
    0    |  0
    0    |  1
    0    |  2

RecipeID | Step
---------------
    0    |  0
    0    |  1
    0    |  2
    1    |  0

How would I generate this type of behavior?

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1 Answer

  1. Editorial Team

    Don’t do this
    Your own question indicates it’s a poor idea.
    How can you have a partial key?
    By definition a partial key cannot be unique.

    The only thing you need from step is an order, Displaying them (or querying them out with say Row_number) as 0 to n is trivial.

    Think about what you would have to do, to insert a step you missed, or swap them…

    RecipeStepID ( as surrogate primary key)

    RecipeID,StepNumber as an index

    Any foreign key links to the table use the surrogate key

    Then re-ordering is just messing about with StepNo

    Never seen the apprioach you are trying not turn into a disaster, and I can count the number of times it didn’t start as a disaster without taking my mittens off.

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