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How to create a Unique (Index) constraint across multiple tables?
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Problem
Is there a way to create a unique index across tables in a SQL Server database?
I have two tables, Table A and Table B. In that I have a Column named ID, I want to make these Id columns as unique (combining Table A and B's Ids )
How can I do this ?
I have two tables, Table A and Table B. In that I have a Column named ID, I want to make these Id columns as unique (combining Table A and B's Ids )
How can I do this ?
Solution
You could use a sequence for generating the values for ID fields. The documentation explicitly mentions your use case. The example C on said page has a sample implementation about this.
Use sequences instead of identity columns in the following scenarios:
between multiple tables or multiple columns within a table.
Be aware that there are a few catches. For example, sequence values are reusable, are not unique by default and can contain gaps. Pay attention to the Limits part in the docs.
Use sequences instead of identity columns in the following scenarios:
- The application requires sharing a single series of numbers
between multiple tables or multiple columns within a table.
Be aware that there are a few catches. For example, sequence values are reusable, are not unique by default and can contain gaps. Pay attention to the Limits part in the docs.
Context
StackExchange Database Administrators Q#143557, answer score: 8
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