25 lines
502 B
Ruby
25 lines
502 B
Ruby
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# frozen_string_literal: true
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class AddUniqueIndexToDevelopers < ActiveRecord::Migration[6.0]
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def up
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execute <<~SQL
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DELETE FROM developers d1
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USING (
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SELECT MAX(id) as id, user_id
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FROM developers
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GROUP BY user_id
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HAVING COUNT(*) > 1
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) d2
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WHERE
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d1.user_id = d2.user_id AND
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d1.id <> d2.id
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SQL
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add_index :developers, %i[user_id], unique: true
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end
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def down
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raise ActiveRecord::IrreversibleMigration
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end
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end
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