MySQL - How to modify column default value?

问题

How do I change my column's default value from None to something else? For example, I want my dates to have a default value of 0000-00-00 if I don't specify one when I create the row.

I understand this in phpMyAdmin, but I'm not sure how to do it via command prompt.

I also understand how to do this when adding a column. But all of my columns are made and have data in some of them.

ALTER TABLE table1 ADD COLUMN foo INT DEFAULT 0;

From searching, I found this line, but I'm not sure if that's what I want?

ALTER TABLE foobar_data MODIFY COLUMN col VARCHAR(255) NOT NULL DEFAULT '{}';

回答1:

Use ALTER TABLE to CHANGE or MODIFY the DEFAULT value of column. Check this link ALTER TABLE SYNTAX

ALTER TABLE `tableName` CHANGE `columnName` `columnName` DATE DEFAULT '0000-00-00'; 
ALTER TABLE `tableName` MODIFY `columnName` DATE DEFAULT '0000-00-00'; 

回答2:

try this

ALTER TABLE foobar_data CHANGE COLUMN col VARCHAR(255) NOT NULL DEFAULT '{}';

user CHANGE to alter a existing column

see Link

回答3:

In my case, it worked

ALTER TABLE `table_name` CHANGE `col_name` `col_name_again` VARCHAR(10) CHARACTER SET latin1 COLLATE latin1_swedish_ci NOT NULL DEFAULT 'anydefault_text';

Hope it helps you too.

来源：https://stackoverflow.com/questions/20917109/mysql-how-to-modify-column-default-value