SQL

default constraint in ms sql

/*Alter an existing column to add a default constraint*/
ALTER TABLE (Table_Name)
ADD CONSTRAINT (Constraint_Name)
DEFAULT (Default_Value) FOR (Existing_Column_Name)

default constraint in ms sql

/*Adding a New Column, with default value to an existing table*/
ALTER TABLE (Table_Name)
ADD (Column_Name)(Data_Type) (Null/NOT NULL)
CONSTRAINT (Constraint_Name) DEFAULT (Default_Value)

SQL DEFAULT Constraint

CREATE TABLE Persons (
    ID int NOT NULL,
    LastName varchar(255) NOT NULL,
    FirstName varchar(255),
    Age int,
    City varchar(255) DEFAULT 'Sandnes'
);

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();