sql add column with default value

1ALTER TABLE users
2ADD visit_number INT DEFAULT 0;

1ALTER TABLE Protocols
2ADD ProtocolTypeID int NOT NULL DEFAULT(1)

1ALTER TABLE PERSON
2ADD IS_ACTIVE VARCHAR2(1) DEFAULT 'N' NOT NULL

1ALTER TABLE {TABLENAME} 
2ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
3CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
4WITH VALUES
5

1ALTER TABLE SomeTable
2        ADD SomeCol Bit NULL --Or NOT NULL.
3 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
4    DEFAULT (0)--Optional Default-Constraint.
5WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.

1ALTER TABLE {TABLENAME} 
2ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL} 
3CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
4WITH VALUES
5
6example 
7
8ALTER TABLE SomeTable
9        ADD SomeCol Bit NULL --Or NOT NULL.
10 CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
11    DEFAULT (0)--Optional Default-Constraint.
12WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.
13