Answers for "add constraint sql default value"

adding a default constraint to an existing column in sql

--Altering an existing column to add a default constraint:
ALTER TABLE {TABLE NAME}
ADD CONSTRAINT {CONSTRAINT NAME}
DEFAULT {DEFAULT VALUE} FOR {EXISTING COLUMN NAME}

--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}

--Dropping a contraint:
ALTER TABLE {TABLE NAME}
DROP CONSTRAINT {CONSTRAINT NAME}

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)