Will Leshner wrote:
On Dec 31, 2003, at 4:56 AM, D. Richard Hipp wrote:
1. There can only be one PRIMARY KEY, but multiple UNIQUE constraints
are allowed.
Ah. This one I didn't know. I thought that multiple columns could
participate in the PRIMARY KEY. But I just tested it and sure enough I
get an error when I try to make more than one column be the PRIMARY KEY.
You CAN have a multi-column primary key. You just have to do it all
at once using a "PRIMARY KEY" clause, not the PRIMARY KEY attribute on
the column. Ex:
CREATE TABLE ex1(
a TEXT,
b VARCHAR(10),
c FLOAT,
PRIMARY KEY(b,a)
);
In the example above, the primary key consists of columns b and a,
in that order.
--
D. Richard Hipp -- [EMAIL PROTECTED] -- 704.948.4565
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