ALTER TABLE ... ADD constraint

Add a constraint to a table.

schema:scott

We can add a constraint

• a foreign key reference
• a UNIQUE requirement
• a CHECK constraint

This is in the SQL standard <a href="http://sqlzoo.net/sql92.html#alter_table_statement">ALTER TABLE</a>

DROP TABLE a

CREATE TABLE a(x INTEGER, y INTEGER);
INSERT INTO a VALUES (1,2);

ALTER TABLE a ADD CHECK (y>0)

The check gets ignored.

The check is not supported.

<a href="http://sqlzoo.napier.ac.uk/big/B/s/a/statements_32a.htm#2103928">ALTER TABLE t DROP COLUMN c</a>

<a href="https://aurora.vcu.edu/db2help/db2s0/frame3.htm#sqls0604"> ALTER TABLE documentation.</a>
DB2 seemingly does not permit this operation - any help would be appreciated.

<a href="http://www.ca.postgresql.org/users-lounge/docs/7.0/user/sql-altertable.htm">ALTER TABLE</a>

CREATE and DROP Operations

CREATE a new table

DROP a table

Composite primary key

CREATE a foreign key

CREATE a VIEW

Autonumber fields

ALTER TABLE ... ADD COLUMN

ALTER TABLE ... DROP COLUMN

ALTER TABLE ... ADD constraint

CREATE TABLE problems: Invalid column name.

CREATE TABLE problems: Insufficient privileges.

CREATE TABLE problems: Table already exists.

DROP TABLE problems: Foreign key references.

CREATE TABLE problems: Foreign key references.

Rename column