On Wed, Jan 08, 2003 at 10:27:30AM -0800, Steven Nakhla wrote:
> Aside from designating a row as a primary key, is
> their any SQL syntax to force that entries within a
> row are unique (such as a string value)? Thanks!
Hello Steve,
You can create a UNIQUE key for a column that will ensure that all
values entered into the column are unique.
i.e.
CREATE TABLE foo (
...,
...,
UNIQUE (...)
)
If you truly want to ensure that a row is unique, then you can create
a UNIQUE key that contains all of the columns in a table.
This will allow you to enter duplicate values within the columns, but
the combination of values (in this case, an entire row) must be
unique.
i.e.
CREATE TABLE combolock (
tumbler_1 INT NOT NULL,
tumbler_2 INT NOT NULL,
tumbler_3 INT NOT NULL,
UNIQUE tumblers (tumbler_1, tumbler_2, tumbler_3)
)
mysql> INSERT INTO combolock VALUES (1,1,1);
Query OK, 1 row affected (0.00 sec)
mysql> INSERT INTO combolock VALUES (1,1,1);
ERROR 1062: Duplicate entry '1-1-1' for key 1
mysql> INSERT INTO combolock VALUES (1,1,2);
Query OK, 1 row affected (0.00 sec)
Cheers!
--
Zak Greant <[EMAIL PROTECTED]> | MySQL Advocate | http://zak.fooassociates.com
Using and Managing MySQL
MySQL Training: Stockholm, February 24-28, 2003
Visit http://mysql.com/training for more information
"While we are postponing, life speeds by." --Lucius Annaeus Seneca
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