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Foreign keys

Applies to ✅ Open Source Edition   ✅ Express Edition   ✅ Professional Edition   ✅ Enterprise Edition

A foreign key is a tool that helps further normalise your database by guaranteeing that a referenced value exists in a parent table. In our sample database, it enforces the integrity of the BOOK.AUTHOR_ID reference. Besides integrity, it can be a very useful tool for optimising more sophisticated execution plans, e.g. to support JOIN elimination. In jOOQ, create foreign keys like this:

// Create a new table with columns and unnamed constraints
create.createTable("table")
      .column("column1", INTEGER)
      .constraints(
          foreignKey("column1").references("other_table", "other_column1")
      )
      .execute();

// Create a new table with columns and named constraints (recommended if you want to alter the constraint)
create.createTable("table")
      .column("column1", INTEGER)
      .constraints(
          constraint("fk").foreignKey("column1").references("other_table", "other_column1")
      )
      .execute();

jOOQ's code generator will pick up foreign keys for a variety of purposes, including navigational methods, the ON KEY joinsand most prominently, the very powerful implicit joins.

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