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Data Types in SQL

Introduction
Modifying columns
Modifying identities
Modifying sequences
Summary
13. Summary

Instruction

It's time to wrap things up! What did we learn?

  1. We only recommend modifying a column by extending the same type (e.g., varchar(32) to varchar(64)). To do so, you can use: 
    ALTER TABLE artwork ALTER COLUMN title SET DATA TYPE varchar(64);
  2. To add auto-generation of an identity, use: 
    ALTER TABLE country ALTER COLUMN id ADD GENERATED ALWAYS AS IDENTITY;
    Similarly, to delete auto-generation of an identity, use: 
    ALTER TABLE country ALTER COLUMN id DROP IDENTITY;
  3. To start a sequence over with a given value, use: 
    ALTER SEQUENCE car_sequence RESTART WITH 1;
  4. To remove a sequence, use: 
    DROP SEQUENCE car_sequence;

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Exercise

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