1/*Alter an existing column to add a default constraint*/
2ALTER TABLE (Table_Name)
3ADD CONSTRAINT (Constraint_Name)
4DEFAULT (Default_Value) FOR (Existing_Column_Name)
5
1/*Adding a New Column, with default value to an existing table*/
2ALTER TABLE (Table_Name)
3ADD (Column_Name)(Data_Type) (Null/NOT NULL)
4CONSTRAINT (Constraint_Name) DEFAULT (Default_Value)