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Updated on 2025-05-17

Oracle plus fields and field annotation SQL statement sample code

Preface

In Oracle database, you can useALTER TABLEStatement to add fields and useCOMMENT ON COLUMNStatement to add field comments. Here is an example:

Suppose you have a name calledemployeestable, you want to add a name calledemailand comment on the field.

1. Add fields

ALTER TABLE employees ADD (email VARCHAR2(100));

2. Add field comments

COMMENT ON COLUMN  IS 'Email address of the employee';

Complete example

-- Add fields
ALTER TABLE employees ADD (email VARCHAR2(100));

-- Add fields注释
COMMENT ON COLUMN  IS 'Email address of the employee';

illustrate

  • ALTER TABLEStatements are used to modify existing table structures.
  • ADD (column_name data_type)Used to add new fields.
  • COMMENT ON COLUMNStatements are used to comment fields, and the annotation content can be any descriptive text to help other developers or database administrators understand the purpose of fields.

If you need to add multiple fields, you canADDAll fields are listed in the clause, for example:

ALTER TABLE employees ADD (email VARCHAR2(100), phone_number VARCHAR2(20));

Then add a comment for each field:

COMMENT ON COLUMN  IS 'Email address of the employee';
COMMENT ON COLUMN employees.phone_number IS 'Employee';

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