CODEWITHSUNDEEP
mysqldatabase
Kedar B
Kedar B

Reputation: 784

create a column with default value as null in mysql database

I want to create a column with default value as null and when any operation is performed it should change to 0. How do i do this in mysql database?

Upvotes: 0

Views: 70

Answers (2)

Sadikhasan
Sadikhasan

Reputation: 18600

Here example how to add colum in existing table with default value

ALTER TABLE `test1` ADD `no` INT NULL DEFAULT NULL ;

When you call function then you have to write following query

UPDATE test1 SET `no` = '0' WHERE `test1`.`id` =your_id;

Upvotes: 1

smali
smali

Reputation: 4805

CREATE TABLE test 
(
id INT NOT NULL AUTO_INCREMENT, 
PRIMARY KEY(id),
test_id INT,
cost FLOAT(5,2) DEFAULT NULL,
);

each time when you do some operation on that you need to update it as @Sadikhasan

or write a trigger that will update it to zero automatically.

if the operation you want to perform is read then write trigger on ON SELECT

if the operation you want to perform is update then write trigger on ON UPDATE

like wise for others.

Upvotes: 0

Related Questions