give default value to column in sql code example

Example 1: add column table sql default value

ALTER TABLE users
ADD visit_number INT DEFAULT 0;

Example 2: how to add default constraint in mysql

ALTER TABLE "name_table" ALTER "name_column" 
SET DEFAULT value_default;

Example 3: set default column value sql

Name Varchar(255) default "Fred"

Example 4: sql default

Sets a default value for a column;
Example 1 (MySQL): Creates a new table called Products which has a
name column with a default value of ‘Placeholder Name’ and an available_
from column with a default value of today’s date.
CREATE TABLE products (
id int,
name varchar(255) DEFAULT 'Placeholder Name',
available_from date DEFAULT GETDATE()
);
Example 2 (MySQL): The same as above, but editing an existing table.
ALTER TABLE products
ALTER name SET DEFAULT 'Placeholder Name',
ALTER available_from SET DEFAULT GETDATE();