Difference between revisions of "ALTER TABLE ... ADD constraint"
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We can add a constraint | We can add a constraint | ||
<ul><li>a foreign key reference</li><li>a UNIQUE requirement</li><li>a CHECK constraint</li></ul> | <ul><li>a foreign key reference</li><li>a UNIQUE requirement</li><li>a CHECK constraint</li></ul> | ||
This is in the SQL standard | This is in the SQL standard [http://sqlzoo.net/sql92.html#alter_table_statement ALTER TABLE] | ||
</div> | </div> | ||
<source lang=sql class='tidy'>DROP TABLE a</source> | <source lang=sql class='tidy'>DROP TABLE a</source> | ||
Revision as of 09:19, 18 July 2012
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 ALTER TABLE
DROP TABLE a
CREATE TABLE a(x INTEGER, y INTEGER);
INSERT INTO a VALUES (1,2);
ALTER TABLE a ADD CHECK (y>0)