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MySQL Tutorial - Add a New Column to an Existing Table

By: FYIcenter.com

(Continued from previous topic...)

How To Add a New Column to an Existing Table?

If you have an existing table with existing data rows, and want to add a new column to that table, you can use the "ALTER TABLE ... ADD COLUMN" statement. The tutorial script below shows you a good example:

mysql> ALTER TABLE tip ADD COLUMN author VARCHAR(40);
Query OK, 1 row affected (0.18 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> SHOW COLUMNS FROM tip;
+-------------+--------------+------+-----+---------+-------
| Field       | Type         | Null | Key | Default | Extra 
+-------------+--------------+------+-----+---------+-------
| id          | int(11)      | NO   | PRI |         |       
| subject     | varchar(80)  | NO   |     |         |       
| description | varchar(256) | NO   |     |         |       
| create_date | date         | YES  |     | NULL    |       
| author      | varchar(40)  | YES  |     | NULL    |       
+-------------+--------------+------+-----+---------+-------
5 rows in set (0.01 sec)

This SQL script added a new column called "author" to the "tip" table. NULL values were added to this column on all existing data rows.

(Continued on next topic...)

  1. What Are DDL Statements?
  2. How To Create a New Table?
  3. What Happens If You No CREATE Privilege in a Database?
  4. How To Get a List of All Tables in a Database?
  5. How To Get a List of Columns in an Existing Table?
  6. How To See the CREATE TABLE Statement of an Existing Table?
  7. How To Create a New Table by Selecting Rows from Another Table?
  8. How To Add a New Column to an Existing Table?
  9. How To Delete an Existing Column in a Table?
  10. How To Rename an Existing Column in a Table?
  11. How To Rename an Existing Table?
  12. How To Drop an Existing Table?
  13. How To Create an Index for a Given Table?
  14. How To Get a List of Indexes of a Given Table?
  15. How To Drop an Existing Index?
  16. How To Create a New View?
  17. How To Drop an Existing View?

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